[SPARK-19110][ML][MLLIB] DistributedLDAModel returns different logPrior for original and loaded model

## What changes were proposed in this pull request?

While adding DistributedLDAModel training summary for SparkR, I found that the logPrior for original and loaded model is different.
For example, in the test("read/write DistributedLDAModel"), I add the test:
val logPrior = model.asInstanceOf[DistributedLDAModel].logPrior
val logPrior2 = model2.asInstanceOf[DistributedLDAModel].logPrior
assert(logPrior === logPrior2)
The test fails:
-4.394180878889078 did not equal -4.294290536919573

The reason is that `graph.vertices.aggregate(0.0)(seqOp, _ + _)` only returns the value of a single vertex instead of the aggregation of all vertices. Therefore, when the loaded model does the aggregation in a different order, it returns different `logPrior`.

Please refer to #16464 for details.
## How was this patch tested?
Add a new unit test for testing logPrior.

Author: wm624@hotmail.com <wm624@hotmail.com>

Closes #16491 from wangmiao1981/ldabug.

## What changes were proposed in this pull request?

`OutputWriterFactory`/`OutputWriter` are internal interfaces and we can remove some unnecessary APIs:
1. `OutputWriterFactory.newWriter(path: String)`: no one calls it and no one implements it.
2. `OutputWriter.write(row: Row)`: during execution we only call `writeInternal`, which is weird as `OutputWriter` is already an internal interface. We should rename `writeInternal` to `write` and remove `def write(row: Row)` and it's related converter code. All implementations should just implement `def write(row: InternalRow)`

## How was this patch tested?

existing tests.

Author: Wenchen Fan <wenchen@databricks.com>

Closes #16479 from cloud-fan/hive-writer.

## What changes were proposed in this pull request?
#16126 bumps master branch version to 2.2.0-SNAPSHOT, but it seems R version was omitted.

## How was this patch tested?
N/A

Author: Yanbo Liang <ybliang8@gmail.com>

Closes #16488 from yanboliang/r-version.

[SPARK-13748][PYSPARK][DOC] Add the description for explictly setting None for a named argument for a Row

## What changes were proposed in this pull request?

It seems allowed to not set a key and value for a dict to represent the value is `None` or missing as below:

``` python
spark.createDataFrame([{"x": 1}, {"y": 2}]).show()
```

```
+----+----+
|   x|   y|
+----+----+
|   1|null|
|null|   2|
+----+----+
```

However,  it seems it is not for `Row` as below:

``` python
spark.createDataFrame([Row(x=1), Row(y=2)]).show()
```

``` scala
16/06/19 16:25:56 ERROR Executor: Exception in task 6.0 in stage 66.0 (TID 316)
java.lang.IllegalStateException: Input row doesn't have expected number of values required by the schema. 2 fields are required while 1 values are provided.
    at org.apache.spark.sql.execution.python.EvaluatePython$.fromJava(EvaluatePython.scala:147)
    at org.apache.spark.sql.SparkSession$$anonfun$7.apply(SparkSession.scala:656)
    at org.apache.spark.sql.SparkSession$$anonfun$7.apply(SparkSession.scala:656)
    at scala.collection.Iterator$$anon$11.next(Iterator.scala:409)
    at scala.collection.Iterator$$anon$11.next(Iterator.scala:409)
    at org.apache.spark.sql.execution.SparkPlan$$anonfun$4.apply(SparkPlan.scala:247)
    at org.apache.spark.sql.execution.SparkPlan$$anonfun$4.apply(SparkPlan.scala:240)
    at org.apache.spark.rdd.RDD$$anonfun$mapPartitionsInternal$1$$anonfun$apply$24.apply(RDD.scala:780)
```

The behaviour seems right but it seems it might confuse users just like this JIRA was reported.

This PR adds the explanation for `Row` class.
## How was this patch tested?

N/A

Author: hyukjinkwon <gurwls223@gmail.com>

Closes #13771 from HyukjinKwon/SPARK-13748.

## What changes were proposed in this pull request?

Added instrumentation logging for OneVsRest classifier, CrossValidator, TrainValidationSplit fit() functions.

## How was this patch tested?

Ran unit tests and checked the log file (see output in comments).

Author: sueann <sueann@databricks.com>

Closes #16480 from sueann/SPARK-18194.

[SPARK-19074][SS][DOCS] Updated Structured Streaming Programming Guide for update mode and source/sink options

## What changes were proposed in this pull request?

Updates
- Updated Late Data Handling section by adding a figure for Update Mode. Its more intuitive to explain late data handling with Update Mode, so I added the new figure before the Append Mode figure.
- Updated Output Modes section with Update mode
- Added options for all the sources and sinks

---------------------------
---------------------------

![image](https://cloud.githubusercontent.com/assets/663212/21665176/f150b224-d29f-11e6-8372-14d32da21db9.png)

---------------------------
---------------------------
<img width="931" alt="screen shot 2017-01-03 at 6 09 11 pm" src="https://cloud.githubusercontent.com/assets/663212/21629740/d21c9bb8-d1df-11e6-915b-488a59589fa6.png">
<img width="933" alt="screen shot 2017-01-03 at 6 10 00 pm" src="https://cloud.githubusercontent.com/assets/663212/21629749/e22bdabe-d1df-11e6-86d3-7e51d2f28dbc.png">

---------------------------
---------------------------
![image](https://cloud.githubusercontent.com/assets/663212/21665200/108e18fc-d2a0-11e6-8640-af598cab090b.png)
![image](https://cloud.githubusercontent.com/assets/663212/21665148/cfe414fa-d29f-11e6-9baa-4124ccbab093.png)
![image](https://cloud.githubusercontent.com/assets/663212/21665226/2e8f39e4-d2a0-11e6-85b1-7657e2df5491.png)

Author: Tathagata Das <tathagata.das1565@gmail.com>

Closes #16468 from tdas/SPARK-19074.

JIRA Issue: https://issues.apache.org/jira/browse/SPARK-19083#

sbin/start-history-server.sh script use of $ without quotes, this will affect the length of args which used in HistoryServerArguments::parse(args: List[String])

Author: zuotingbing <zuo.tingbing9@zte.com.cn>

Closes #16484 from zuotingbing/sh.

In the existing code, there are three layers of serialization
    involved in sending a task from the scheduler to an executor:
        - A Task object is serialized
        - The Task object is copied to a byte buffer that also
          contains serialized information about any additional JARs,
          files, and Properties needed for the task to execute. This
          byte buffer is stored as the member variable serializedTask
          in the TaskDescription class.
        - The TaskDescription is serialized (in addition to the serialized
          task + JARs, the TaskDescription class contains the task ID and
          other metadata) and sent in a LaunchTask message.

While it *is* necessary to have two layers of serialization, so that
the JAR, file, and Property info can be deserialized prior to
deserializing the Task object, the third layer of deserialization is
unnecessary.  This commit eliminates a layer of serialization by moving
the JARs, files, and Properties into the TaskDescription class.

This commit also serializes the Properties manually (by traversing the map),
as is done with the JARs and files, which reduces the final serialized size.

Unit tests

This is a simpler alternative to the approach proposed in #15505.

shivaram and I did some benchmarking of this and #15505 on a 20-machine m2.4xlarge EC2 machines (160 cores). We ran ~30 trials of code [1] (a very simple job with 10K tasks per stage) and measured the average time per stage:

Before this change: 2490ms
With this change: 2345 ms (so ~6% improvement over the baseline)
With witgo's approach in #15505: 2046 ms (~18% improvement over baseline)

The reason that #15505 has a more significant improvement is that it also moves the serialization from the TaskSchedulerImpl thread to the CoarseGrainedSchedulerBackend thread. I added that functionality on top of this change, and got almost the same improvement [1] as #15505 (average of 2103ms). I think we should decouple these two changes, both so we have some record of the improvement form each individual improvement, and because this change is more about simplifying the code base (the improvement is negligible) while the other is about performance improvement.  The plan, currently, is to merge this PR and then merge the remaining part of #15505 that moves serialization.

[1] The reason the improvement wasn't quite as good as with #15505 when we ran the benchmarks is almost certainly because, at the point when we ran the benchmarks, I hadn't updated the code to manually serialize the Properties (instead the code was using Java's default serialization for the Properties object, whereas #15505 manually serialized the Properties).  This PR has since been updated to manually serialize the Properties, just like the other maps.

Author: Kay Ousterhout <kayousterhout@gmail.com>

Closes #16053 from kayousterhout/SPARK-17931.

## What changes were proposed in this pull request?

Current HistoryServer's ACLs is derived from application event-log, which means the newly changed ACLs cannot be applied to the old data, this will become a problem where newly added admin cannot access the old application history UI, only the new application can be affected.

So here propose to add admin ACLs for history server, any configured user/group could have the view access to all the applications, while the view ACLs derived from application run-time still take effect.

## How was this patch tested?

Unit test added.

Author: jerryshao <sshao@hortonworks.com>

Closes #16470 from jerryshao/SPARK-19033.

[SPARK-16792][SQL] Dataset containing a Case Class with a List type causes a CompileException (converting sequence to list)

## What changes were proposed in this pull request?

Added a `to` call at the end of the code generated by `ScalaReflection.deserializerFor` if the requested type is not a supertype of `WrappedArray[_]` that uses `CanBuildFrom[_, _, _]` to convert result into an arbitrary subtype of `Seq[_]`.

Care was taken to preserve the original deserialization where it is possible to avoid the overhead of conversion in cases where it is not needed

`ScalaReflection.serializerFor` could already be used to serialize any `Seq[_]` so it was not altered

`SQLImplicits` had to be altered and new implicit encoders added to permit serialization of other sequence types

Also fixes [SPARK-16815] Dataset[List[T]] leads to ArrayStoreException

## How was this patch tested?
```bash
./build/mvn -DskipTests clean package && ./dev/run-tests
```

Also manual execution of the following sets of commands in the Spark shell:
```scala
case class TestCC(key: Int, letters: List[String])

val ds1 = sc.makeRDD(Seq(
(List("D")),
(List("S","H")),
(List("F","H")),
(List("D","L","L"))
)).map(x=>(x.length,x)).toDF("key","letters").as[TestCC]

val test1=ds1.map{_.key}
test1.show
```

```scala
case class X(l: List[String])
spark.createDataset(Seq(List("A"))).map(X).show
```

```scala
spark.sqlContext.createDataset(sc.parallelize(List(1) :: Nil)).collect
```

After adding arbitrary sequence support also tested with the following commands:

```scala
case class QueueClass(q: scala.collection.immutable.Queue[Int])

spark.createDataset(Seq(List(1,2,3))).map(x => QueueClass(scala.collection.immutable.Queue(x: _*))).map(_.q.dequeue).collect
```

Author: Michal Senkyr <mike.senkyr@gmail.com>

Closes #16240 from michalsenkyr/sql-caseclass-list-fix.

## What changes were proposed in this pull request?
This PR extends the existing IN/NOT IN subquery test cases coverage, adds more test cases to the IN subquery test suite.

Based on the discussion, we will create  `subquery/in-subquery` sub structure under `sql/core/src/test/resources/sql-tests/inputs` directory.

This is the high level grouping for IN subquery:

`subquery/in-subquery/`
`subquery/in-subquery/simple-in.sql`
`subquery/in-subquery/in-group-by.sql (in parent side, subquery, and both)`
`subquery/in-subquery/not-in-group-by.sql`
`subquery/in-subquery/in-order-by.sql`
`subquery/in-subquery/in-limit.sql`
`subquery/in-subquery/in-having.sql`
`subquery/in-subquery/in-joins.sql`
`subquery/in-subquery/not-in-joins.sql`
`subquery/in-subquery/in-set-operations.sql`
`subquery/in-subquery/in-with-cte.sql`
`subquery/in-subquery/not-in-with-cte.sql`
subquery/in-subquery/in-multiple-columns.sql`

We will deliver it through multiple prs, this is the first pr for the IN subquery, it has

`subquery/in-subquery/simple-in.sql`
`subquery/in-subquery/in-group-by.sql (in parent side, subquery, and both)`

These are the results from running on DB2.
[Modified test file of in-group-by.sql used to run on DB2](https://github.com/apache/spark/files/683367/in-group-by.sql.db2.txt)
[Output of the run result on DB2](https://github.com/apache/spark/files/683362/in-group-by.sql.db2.out.txt)
[Modified test file of simple-in.sql used to run on DB2](https://github.com/apache/spark/files/683378/simple-in.sql.db2.txt)
[Output of the run result on DB2](https://github.com/apache/spark/files/683379/simple-in.sql.db2.out.txt)

## How was this patch tested?

This patch is adding tests.

Author: Kevin Yu <qyu@us.ibm.com>

Closes #16337 from kevinyu98/spark-18871.

## What changes were proposed in this pull request?
Set correct column names for ```force to use probability2prediction``` in ```LogisticRegressionSuite```.

## How was this patch tested?
Change unit test.

Author: Yanbo Liang <ybliang8@gmail.com>

Closes #16477 from yanboliang/lor-pred.

## What changes were proposed in this pull request?

Today we have different syntax to create data source or hive serde tables, we should unify them to not confuse users and step forward to make hive a data source.

Please read https://issues.apache.org/jira/secure/attachment/12843835/CREATE-TABLE.pdf for  details.

TODO(for follow-up PRs):
1. TBLPROPERTIES is not added to the new syntax, we should decide if we wanna add it later.
2. `SHOW CREATE TABLE` should be updated to use the new syntax.
3. we should decide if we wanna change the behavior of `SET LOCATION`.

## How was this patch tested?

new tests

Author: Wenchen Fan <wenchen@databricks.com>

Closes #16296 from cloud-fan/create-table.

## What changes were proposed in this pull request?

TaskResultGetter tries to deserialize the TaskEndReason before handling the failed task. If an error is thrown during deserialization, the failed task won't be handled, which leaves the job hanging.
The PR proposes to handle the failed task in a finally block.
## How was this patch tested?

In my case I hit a NoClassDefFoundError and the job hangs. Manually verified the patch can fix it.

Author: Rui Li <rui.li@intel.com>
Author: Rui Li <lirui@apache.org>
Author: Rui Li <shlr@cn.ibm.com>

Closes #12775 from lirui-intel/SPARK-14958.

## What changes were proposed in this pull request?

When we append data to a partitioned table with `DataFrameWriter.saveAsTable`, there are 2 issues:
1. doesn't work when the partition has custom location.
2. will recover all partitions

This PR fixes them by moving the special partition handling code from `DataSourceAnalysis` to `InsertIntoHadoopFsRelationCommand`, so that the `DataFrameWriter.saveAsTable` code path can also benefit from it.

## How was this patch tested?

newly added regression tests

Author: Wenchen Fan <wenchen@databricks.com>

Closes #16460 from cloud-fan/append.

## What changes were proposed in this pull request?

add streaming rest api doc

related to pr #16253

cc saturday-shi srowen

## How was this patch tested?

Author: uncleGen <hustyugm@gmail.com>

Closes #16414 from uncleGen/SPARK-19009.

This commit changes Utils.writeByteBuffer so that it does not change
the position of the ByteBuffer that it writes out, and adds a unit test for
this functionality.

cc mridulm

Author: Kay Ousterhout <kayousterhout@gmail.com>

Closes #16462 from kayousterhout/SPARK-19062.

## What changes were proposed in this pull request?
Dataset actions currently spin off a new `Dataframe` only to track query execution. This PR simplifies this code path by using the `Dataset.queryExecution` directly. This PR also merges the typed and untyped action evaluation paths.

## How was this patch tested?
Existing tests.

Author: Herman van Hovell <hvanhovell@databricks.com>

Closes #16466 from hvanhovell/SPARK-19070.

## What changes were proposed in this pull request?
There are many locations in the Spark repo where the same word occurs consecutively. Sometimes they are appropriately placed, but many times they are not. This PR removes the inappropriately duplicated words.

## How was this patch tested?
N/A since only docs or comments were updated.

Author: Niranjan Padmanabhan <niranjan.padmanabhan@gmail.com>

Closes #16455 from neurons/np.structure_streaming_doc.

## What changes were proposed in this pull request?
eliminate unnecessary extra pass in NB's train

## How was this patch tested?
existing tests

Author: Zheng RuiFeng <ruifengz@foxmail.com>

Closes #16453 from zhengruifeng/nb_getNC.

## What changes were proposed in this pull request?

Now all aggregation functions support partial aggregate, we can remove the `supportsPartual` flag in `AggregateFunction`

## How was this patch tested?

existing tests.

Author: Wenchen Fan <wenchen@databricks.com>

Closes #16461 from cloud-fan/partial.

## What changes were proposed in this pull request?
LauncherState should be only set to SUBMITTED after the application is submitted.
Currently the state is set before the application is actually submitted.

## How was this patch tested?
no test is added in this patch

Author: mingfei <mingfei.smf@alipay.com>

Closes #16459 from shimingfei/fixLauncher.

## What changes were proposed in this pull request?

In https://github.com/apache/spark/pull/16402 we made a mistake that, when double/float is infinity, the `Literal` codegen will output boxed value and cause wrong result.

This PR fixes this by special handling infinity to not output boxed value.

## How was this patch tested?

new regression test

Author: Wenchen Fan <wenchen@databricks.com>

Closes #16469 from cloud-fan/literal.

[SPARK-19048][SQL] Delete Partition Location when Dropping Managed Partitioned Tables in InMemoryCatalog

### What changes were proposed in this pull request?
The data in the managed table should be deleted after table is dropped. However, if the partition location is not under the location of the partitioned table, it is not deleted as expected. Users can specify any location for the partition when they adding a partition.

This PR is to delete partition location when dropping managed partitioned tables stored in `InMemoryCatalog`.

### How was this patch tested?
Added test cases for both HiveExternalCatalog and InMemoryCatalog

Author: gatorsmile <gatorsmile@gmail.com>

Closes #16448 from gatorsmile/unsetSerdeProp.

## What changes were proposed in this pull request?

Not adding the Killed applications for retry.
## How was this patch tested?

I have verified manually in the Mesos cluster, with the changes the killed applications move to Finished Drivers section and will not retry.

Author: Devaraj K <devaraj@apache.org>

Closes #13323 from devaraj-kavali/SPARK-15555.

[SPARK-18877][SQL] `CSVInferSchema.inferField` on DecimalType should find a common type with `typeSoFar`

## What changes were proposed in this pull request?

CSV type inferencing causes `IllegalArgumentException` on decimal numbers with heterogeneous precisions and scales because the current logic uses the last decimal type in a **partition**. Specifically, `inferRowType`, the **seqOp** of **aggregate**, returns the last decimal type. This PR fixes it to use `findTightestCommonType`.

**decimal.csv**
```
9.03E+12
1.19E+11
```

**BEFORE**
```scala
scala> spark.read.format("csv").option("inferSchema", true).load("decimal.csv").printSchema
root
 |-- _c0: decimal(3,-9) (nullable = true)

scala> spark.read.format("csv").option("inferSchema", true).load("decimal.csv").show
16/12/16 14:32:49 ERROR Executor: Exception in task 0.0 in stage 4.0 (TID 4)
java.lang.IllegalArgumentException: requirement failed: Decimal precision 4 exceeds max precision 3
```

**AFTER**
```scala
scala> spark.read.format("csv").option("inferSchema", true).load("decimal.csv").printSchema
root
 |-- _c0: decimal(4,-9) (nullable = true)

scala> spark.read.format("csv").option("inferSchema", true).load("decimal.csv").show
+---------+
|      _c0|
+---------+
|9.030E+12|
| 1.19E+11|
+---------+
```

## How was this patch tested?

Pass the newly add test case.

Author: Dongjoon Hyun <dongjoon@apache.org>

Closes #16320 from dongjoon-hyun/SPARK-18877.

## What changes were proposed in this pull request?

Currently collect_set/collect_list aggregation expression don't support partial aggregation. This patch is to enable partial aggregation for them.

## How was this patch tested?

Jenkins tests.

Please review http://spark.apache.org/contributing.html before opening a pull request.

Author: Liang-Chi Hsieh <viirya@gmail.com>

Closes #16371 from viirya/collect-partial-support.

## What changes were proposed in this pull request?

Add `finally` clause for `sc.stop()` in the `test("register and deregister Spark listener from SparkContext")`.

## How was this patch tested?
Pass the build and unit tests.

Author: Weiqing Yang <yangweiqing001@gmail.com>

Closes #16426 from weiqingy/testIssue.

## What changes were proposed in this pull request?

We add a cbo configuration to switch between default stats and estimated stats.
We also define a new statistics method `planStats` in LogicalPlan with conf as its parameter, in order to pass the cbo switch and other estimation related configurations in the future. `planStats` is used on the caller sides (i.e. in Optimizer and Strategies) to make transformation decisions based on stats.

## How was this patch tested?

Add a test case using a dummy LogicalPlan.

Author: Zhenhua Wang <wzh_zju@163.com>

Closes #16401 from wzhfy/cboSwitch.

### What changes were proposed in this pull request?
Remove useless `databaseName ` from `SimpleCatalogRelation`.

### How was this patch tested?
Existing test cases.

Author: gatorsmile <gatorsmile@gmail.com>

Closes #16438 from gatorsmile/removeDBFromSimpleCatalogRelation.

## What changes were proposed in this pull request?

This PR proposes to check pep8 against all other Python scripts and fix the errors as below:

```bash
./dev/create-release/generate-contributors.py
./dev/create-release/releaseutils.py
./dev/create-release/translate-contributors.py
./dev/lint-python
./python/docs/epytext.py
./examples/src/main/python/mllib/decision_tree_classification_example.py
./examples/src/main/python/mllib/decision_tree_regression_example.py
./examples/src/main/python/mllib/gradient_boosting_classification_example.py
./examples/src/main/python/mllib/gradient_boosting_regression_example.py
./examples/src/main/python/mllib/linear_regression_with_sgd_example.py
./examples/src/main/python/mllib/logistic_regression_with_lbfgs_example.py
./examples/src/main/python/mllib/naive_bayes_example.py
./examples/src/main/python/mllib/random_forest_classification_example.py
./examples/src/main/python/mllib/random_forest_regression_example.py
./examples/src/main/python/mllib/svm_with_sgd_example.py
./examples/src/main/python/streaming/network_wordjoinsentiments.py
./sql/hive/src/test/resources/data/scripts/cat.py
./sql/hive/src/test/resources/data/scripts/cat_error.py
./sql/hive/src/test/resources/data/scripts/doubleescapedtab.py
./sql/hive/src/test/resources/data/scripts/dumpdata_script.py
./sql/hive/src/test/resources/data/scripts/escapedcarriagereturn.py
./sql/hive/src/test/resources/data/scripts/escapednewline.py
./sql/hive/src/test/resources/data/scripts/escapedtab.py
./sql/hive/src/test/resources/data/scripts/input20_script.py
./sql/hive/src/test/resources/data/scripts/newline.py
```

## How was this patch tested?

- `./python/docs/epytext.py`

  ```bash
  cd ./python/docs $$ make html
  ```

- pep8 check (Python 2.7 / Python 3.3.6)

  ```
  ./dev/lint-python
  ```

- `./dev/merge_spark_pr.py` (Python 2.7 only / Python 3.3.6 not working)

  ```bash
  python -m doctest -v ./dev/merge_spark_pr.py
  ```

- `./dev/create-release/releaseutils.py` `./dev/create-release/generate-contributors.py` `./dev/create-release/translate-contributors.py` (Python 2.7 only / Python 3.3.6 not working)

  ```bash
  python generate-contributors.py
  python translate-contributors.py
  ```

- Examples (Python 2.7 / Python 3.3.6)

  ```bash
  ./bin/spark-submit examples/src/main/python/mllib/decision_tree_classification_example.py
  ./bin/spark-submit examples/src/main/python/mllib/decision_tree_regression_example.py
  ./bin/spark-submit examples/src/main/python/mllib/gradient_boosting_classification_example.py
  ./bin/spark-submit examples/src/main/python/mllib/gradient_boosting_regression_example.p
  ./bin/spark-submit examples/src/main/python/mllib/random_forest_classification_example.py
  ./bin/spark-submit examples/src/main/python/mllib/random_forest_regression_example.py
  ```

- Examples (Python 2.7 only / Python 3.3.6 not working)
  ```
  ./bin/spark-submit examples/src/main/python/mllib/linear_regression_with_sgd_example.py
  ./bin/spark-submit examples/src/main/python/mllib/logistic_regression_with_lbfgs_example.py
  ./bin/spark-submit examples/src/main/python/mllib/naive_bayes_example.py
  ./bin/spark-submit examples/src/main/python/mllib/svm_with_sgd_example.py
  ```

- `sql/hive/src/test/resources/data/scripts/*.py` (Python 2.7 / Python 3.3.6 within suggested changes)

  Manually tested only changed ones.

- `./dev/github_jira_sync.py` (Python 2.7 only / Python 3.3.6 not working)

  Manually tested this after disabling actually adding comments and links.

And also via Jenkins tests.

Author: hyukjinkwon <gurwls223@gmail.com>

Closes #16405 from HyukjinKwon/minor-pep8.

## What changes were proposed in this pull request?

There are two tests failing on Windows due to the different newlines.

```
 - StreamingQueryProgress - prettyJson *** FAILED *** (0 milliseconds)
 "{
    "id" : "39788670-6722-48b7-a248-df6ba08722ac",
    "runId" : "422282f1-3b81-4b47-a15d-82dda7e69390",
    "name" : "myName",
    ...
  }" did not equal "{
    "id" : "39788670-6722-48b7-a248-df6ba08722ac",
    "runId" : "422282f1-3b81-4b47-a15d-82dda7e69390",
    "name" : "myName",
    ...
  }"
  ...
```

```
 - StreamingQueryStatus - prettyJson *** FAILED *** (0 milliseconds)
 "{
    "message" : "active",
    "isDataAvailable" : true,
    "isTriggerActive" : false
  }" did not equal "{
    "message" : "active",
    "isDataAvailable" : true,
    "isTriggerActive" : false
  }"
  ...
```

The reason is, `pretty` in `org.json4s.pretty` writes OS-dependent newlines but the string defined in the tests are `\n`. This ends up with test failures.

This PR proposes to compare these regardless of newline concerns.

## How was this patch tested?

Manually tested via AppVeyor.

**Before**
https://ci.appveyor.com/project/spark-test/spark/build/417-newlines-fix-before

**After**
https://ci.appveyor.com/project/spark-test/spark/build/418-newlines-fix

Author: hyukjinkwon <gurwls223@gmail.com>

Closes #16433 from HyukjinKwon/tests-StreamingQueryStatusAndProgressSuite.

## What changes were proposed in this pull request?

The configuration `spark.yarn.security.tokens.{service}.enabled` is deprecated. Now we should use `spark.yarn.security.credentials.{service}.enabled`. Some places in the doc is not updated yet.

## How was this patch tested?

N/A. Just doc change.

Please review http://spark.apache.org/contributing.html before opening a pull request.

Author: Liang-Chi Hsieh <viirya@gmail.com>

Closes #16444 from viirya/minor-credential-provider-doc.

## What changes were proposed in this pull request?

Currently some code snippets in the programming guide just do not compile. We should fix them.

## How was this patch tested?

```
SKIP_API=1 jekyll build
```

## Screenshot from part of the change:

![snip20161231_37](https://cloud.githubusercontent.com/assets/15843379/21576864/cc52fcd8-cf7b-11e6-8bd6-f935d9ff4a6b.png)

Author: Liwei Lin <lwlin7@gmail.com>

Closes #16442 from lw-lin/ss-pro-guide-.

Closes #12968
Closes #16215
Closes #16212
Closes #16086
Closes #15713
Closes #16413
Closes #16396

Author: Sean Owen <sowen@cloudera.com>

Closes #16447 from srowen/CloseStalePRs.

## What changes were proposed in this pull request?

`monthsSinceEpoch` in this test is like `math.floor(num)`, so `monthDiff` has two possible values.

## How was this patch tested?

Jenkins.

Author: Shixiong Zhu <shixiong@databricks.com>

Closes #16449 from zsxwing/watermark-test-hotfix.

### What changes were proposed in this pull request?
Fixed non-thread-safe functions used in SessionCatalog:
- refreshTable
- lookupRelation

### How was this patch tested?
N/A

Author: gatorsmile <gatorsmile@gmail.com>

Closes #16437 from gatorsmile/addSyncToLookUpTable.

## What changes were proposed in this pull request?

This PR documents the scalable partition handling feature in the body of the programming guide.

Before this PR, we only mention it in the migration guide. It's not super clear that external datasource tables require an extra `MSCK REPAIR TABLE` command is to have per-partition information persisted since 2.1.

## How was this patch tested?

N/A.

Author: Cheng Lian <lian@databricks.com>

Closes #16424 from liancheng/scalable-partition-handling-doc.

## What changes were proposed in this pull request?

Apache Spark supports the following cases **by quoting RDD column names** while saving through JDBC.
- Allow reserved keyword as a column name, e.g., 'order'.
- Allow mixed-case colume names like the following, e.g., `[a: int, A: int]`.

  ``` scala
  scala> val df = sql("select 1 a, 1 A")
  df: org.apache.spark.sql.DataFrame = [a: int, A: int]
  ...
  scala> df.write.mode("overwrite").format("jdbc").options(option).save()
  scala> df.write.mode("append").format("jdbc").options(option).save()
  ```

This PR aims to use **database column names** instead of RDD column ones in order to support the following additionally.
Note that this case succeeds with `MySQL`, but fails on `Postgres`/`Oracle` before.

``` scala
val df1 = sql("select 1 a")
val df2 = sql("select 1 A")
...
df1.write.mode("overwrite").format("jdbc").options(option).save()
df2.write.mode("append").format("jdbc").options(option).save()
```
## How was this patch tested?

Pass the Jenkins test with a new testcase.

Author: Dongjoon Hyun <dongjoon@apache.org>
Author: gatorsmile <gatorsmile@gmail.com>

Closes #15664 from dongjoon-hyun/SPARK-18123.

## What changes were proposed in this pull request?

This PR proposes to fix the test failures due to different format of paths on Windows.

Failed tests are as below:

```
ColumnExpressionSuite:
- input_file_name, input_file_block_start, input_file_block_length - FileScanRDD *** FAILED *** (187 milliseconds)
  "file:///C:/projects/spark/target/tmp/spark-0b21b963-6cfa-411c-8d6f-e6a5e1e73bce/part-00001-c083a03a-e55e-4b05-9073-451de352d006.snappy.parquet" did not contain "C:\projects\spark\target\tmp\spark-0b21b963-6cfa-411c-8d6f-e6a5e1e73bce" (ColumnExpressionSuite.scala:545)

- input_file_name, input_file_block_start, input_file_block_length - HadoopRDD *** FAILED *** (172 milliseconds)
  "file:/C:/projects/spark/target/tmp/spark-5d0afa94-7c2f-463b-9db9-2e8403e2bc5f/part-00000-f6530138-9ad3-466d-ab46-0eeb6f85ed0b.txt" did not contain "C:\projects\spark\target\tmp\spark-5d0afa94-7c2f-463b-9db9-2e8403e2bc5f" (ColumnExpressionSuite.scala:569)

- input_file_name, input_file_block_start, input_file_block_length - NewHadoopRDD *** FAILED *** (156 milliseconds)
  "file:/C:/projects/spark/target/tmp/spark-a894c7df-c74d-4d19-82a2-a04744cb3766/part-00000-29674e3f-3fcf-4327-9b04-4dab1d46338d.txt" did not contain "C:\projects\spark\target\tmp\spark-a894c7df-c74d-4d19-82a2-a04744cb3766" (ColumnExpressionSuite.scala:598)
```

```
DataStreamReaderWriterSuite:
- source metadataPath *** FAILED *** (62 milliseconds)
  org.mockito.exceptions.verification.junit.ArgumentsAreDifferent: Argument(s) are different! Wanted:
streamSourceProvider.createSource(
    org.apache.spark.sql.SQLContext3b04133b,
    "C:\projects\spark\target\tmp\streaming.metadata-b05db6ae-c8dc-4ce4-b0d9-1eb8c84876c0/sources/0",
    None,
    "org.apache.spark.sql.streaming.test",
    Map()
);
-> at org.apache.spark.sql.streaming.test.DataStreamReaderWriterSuite$$anonfun$12.apply$mcV$sp(DataStreamReaderWriterSuite.scala:374)
Actual invocation has different arguments:
streamSourceProvider.createSource(
    org.apache.spark.sql.SQLContext3b04133b,
    "/C:/projects/spark/target/tmp/streaming.metadata-b05db6ae-c8dc-4ce4-b0d9-1eb8c84876c0/sources/0",
    None,
    "org.apache.spark.sql.streaming.test",
    Map()
);
```

```
GlobalTempViewSuite:
- CREATE GLOBAL TEMP VIEW USING *** FAILED *** (110 milliseconds)
  org.apache.spark.sql.AnalysisException: Path does not exist: file:/C:projectsspark  arget mpspark-960398ba-a0a1-45f6-a59a-d98533f9f519;
```

```
CreateTableAsSelectSuite:
- CREATE TABLE USING AS SELECT *** FAILED *** (0 milliseconds)
  java.lang.IllegalArgumentException: Can not create a Path from an empty string

- create a table, drop it and create another one with the same name *** FAILED *** (16 milliseconds)
  java.lang.IllegalArgumentException: Can not create a Path from an empty string

- create table using as select - with partitioned by *** FAILED *** (0 milliseconds)
  java.lang.IllegalArgumentException: Can not create a Path from an empty string

- create table using as select - with non-zero buckets *** FAILED *** (0 milliseconds)
  java.lang.IllegalArgumentException: Can not create a Path from an empty string
```

```
HiveMetadataCacheSuite:
- partitioned table is cached when partition pruning is true *** FAILED *** (532 milliseconds)
  org.apache.spark.sql.AnalysisException: org.apache.hadoop.hive.ql.metadata.HiveException: MetaException(message:java.lang.IllegalArgumentException: Can not create a Path from an empty string);

- partitioned table is cached when partition pruning is false *** FAILED *** (297 milliseconds)
  org.apache.spark.sql.AnalysisException: org.apache.hadoop.hive.ql.metadata.HiveException: MetaException(message:java.lang.IllegalArgumentException: Can not create a Path from an empty string);
```

```
MultiDatabaseSuite:
- createExternalTable() to non-default database - with USE *** FAILED *** (954 milliseconds)
  org.apache.spark.sql.AnalysisException: Path does not exist: file:/C:projectsspark  arget mpspark-0839d9a7-5e29-467a-9e3e-3e4cd618ee09;

- createExternalTable() to non-default database - without USE *** FAILED *** (500 milliseconds)
  org.apache.spark.sql.AnalysisException: Path does not exist: file:/C:projectsspark  arget mpspark-c7e24d73-1d8f-45e8-ab7d-53a83087aec3;

 - invalid database name and table names *** FAILED *** (31 milliseconds)
   "Path does not exist: file:/C:projectsspark  arget mpspark-15a2a494-3483-4876-80e5-ec396e704b77;" did not contain "`t:a` is not a valid name for tables/databases. Valid names only contain alphabet characters, numbers and _." (MultiDatabaseSuite.scala:296)
```

```
OrcQuerySuite:
 - SPARK-8501: Avoids discovery schema from empty ORC files *** FAILED *** (15 milliseconds)
   org.apache.spark.sql.AnalysisException: org.apache.hadoop.hive.ql.metadata.HiveException: MetaException(message:java.lang.IllegalArgumentException: Can not create a Path from an empty string);

 - Verify the ORC conversion parameter: CONVERT_METASTORE_ORC *** FAILED *** (78 milliseconds)
   org.apache.spark.sql.AnalysisException: org.apache.hadoop.hive.ql.metadata.HiveException: MetaException(message:java.lang.IllegalArgumentException: Can not create a Path from an empty string);

 - converted ORC table supports resolving mixed case field *** FAILED *** (297 milliseconds)
   org.apache.spark.sql.AnalysisException: org.apache.hadoop.hive.ql.metadata.HiveException: MetaException(message:java.lang.IllegalArgumentException: Can not create a Path from an empty string);
```

```
HadoopFsRelationTest - JsonHadoopFsRelationSuite, OrcHadoopFsRelationSuite, ParquetHadoopFsRelationSuite, SimpleTextHadoopFsRelationSuite:
 - Locality support for FileScanRDD *** FAILED *** (15 milliseconds)
   java.lang.IllegalArgumentException: Wrong FS: file://C:\projects\spark\target\tmp\spark-383d1f13-8783-47fd-964d-9c75e5eec50f, expected: file:///
```

```
HiveQuerySuite:
- CREATE TEMPORARY FUNCTION *** FAILED *** (0 milliseconds)
   java.net.MalformedURLException: For input string: "%5Cprojects%5Cspark%5Csql%5Chive%5Ctarget%5Cscala-2.11%5Ctest-classes%5CTestUDTF.jar"

 - ADD FILE command *** FAILED *** (500 milliseconds)
   java.net.URISyntaxException: Illegal character in opaque part at index 2: C:\projects\spark\sql\hive\target\scala-2.11\test-classes\data\files\v1.txt

 - ADD JAR command 2 *** FAILED *** (110 milliseconds)
   org.apache.spark.sql.AnalysisException: LOAD DATA input path does not exist: C:projectssparksqlhive  argetscala-2.11 est-classesdatafilessample.json;
```

```
PruneFileSourcePartitionsSuite:
 - PruneFileSourcePartitions should not change the output of LogicalRelation *** FAILED *** (15 milliseconds)
   org.apache.spark.sql.AnalysisException: org.apache.hadoop.hive.ql.metadata.HiveException: MetaException(message:java.lang.IllegalArgumentException: Can not create a Path from an empty string);
```

```
HiveCommandSuite:
 - LOAD DATA LOCAL *** FAILED *** (109 milliseconds)
   org.apache.spark.sql.AnalysisException: LOAD DATA input path does not exist: C:projectssparksqlhive  argetscala-2.11 est-classesdatafilesemployee.dat;

 - LOAD DATA *** FAILED *** (93 milliseconds)
   java.net.URISyntaxException: Illegal character in opaque part at index 15: C:projectsspark arget mpemployee.dat7496657117354281006.tmp

 - Truncate Table *** FAILED *** (78 milliseconds)
   org.apache.spark.sql.AnalysisException: LOAD DATA input path does not exist: C:projectssparksqlhive  argetscala-2.11 est-classesdatafilesemployee.dat;
```

```
HiveExternalCatalogBackwardCompatibilitySuite:
- make sure we can read table created by old version of Spark *** FAILED *** (0 milliseconds)
  "[/C:/projects/spark/target/tmp/]spark-0554d859-74e1-..." did not equal "[C:\projects\spark\target\tmp\]spark-0554d859-74e1-..." (HiveExternalCatalogBackwardCompatibilitySuite.scala:213)
  org.scalatest.exceptions.TestFailedException

- make sure we can alter table location created by old version of Spark *** FAILED *** (110 milliseconds)
  java.net.URISyntaxException: Illegal character in opaque part at index 15: C:projectsspark	arget	mpspark-0e9b2c5f-49a1-4e38-a32a-c0ab1813a79f
```

```
ExternalCatalogSuite:
- create/drop/rename partitions should create/delete/rename the directory *** FAILED *** (610 milliseconds)
  java.net.URISyntaxException: Illegal character in opaque part at index 2: C:\projects\spark\target\tmp\spark-4c24f010-18df-437b-9fed-990c6f9adece
```

```
SQLQuerySuite:
- describe functions - temporary user defined functions *** FAILED *** (16 milliseconds)
  java.net.URISyntaxException: Illegal character in opaque part at index 22: C:projectssparksqlhive	argetscala-2.11	est-classesTestUDTF.jar

- specifying database name for a temporary table is not allowed *** FAILED *** (125 milliseconds)
  org.apache.spark.sql.AnalysisException: Path does not exist: file:/C:projectsspark	arget	mpspark-a34c9814-a483-43f2-be29-37f616b6df91;
```

```
PartitionProviderCompatibilitySuite:
- convert partition provider to hive with repair table *** FAILED *** (281 milliseconds)
  org.apache.spark.sql.AnalysisException: Path does not exist: file:/C:projectsspark	arget	mpspark-ee5fc96d-8c7d-4ebf-8571-a1d62736473e;

- when partition management is enabled, new tables have partition provider hive *** FAILED *** (187 milliseconds)
  org.apache.spark.sql.AnalysisException: Path does not exist: file:/C:projectsspark	arget	mpspark-803ad4d6-3e8c-498d-9ca5-5cda5d9b2a48;

- when partition management is disabled, new tables have no partition provider *** FAILED *** (172 milliseconds)
  org.apache.spark.sql.AnalysisException: Path does not exist: file:/C:projectsspark	arget	mpspark-c9fda9e2-4020-465f-8678-52cd72d0a58f;

- when partition management is disabled, we preserve the old behavior even for new tables *** FAILED *** (203 milliseconds)
  org.apache.spark.sql.AnalysisException: Path does not exist: file:/C:projectsspark	arget
mpspark-f4a518a6-c49d-43d3-b407-0ddd76948e13;

- insert overwrite partition of legacy datasource table *** FAILED *** (188 milliseconds)
  org.apache.spark.sql.AnalysisException: Path does not exist: file:/C:projectsspark	arget	mpspark-f4a518a6-c49d-43d3-b407-0ddd76948e79;

- insert overwrite partition of new datasource table overwrites just partition *** FAILED *** (219 milliseconds)
  org.apache.spark.sql.AnalysisException: Path does not exist: file:/C:projectsspark	arget	mpspark-6ba3a88d-6f6c-42c5-a9f4-6d924a0616ff;

- SPARK-18544 append with saveAsTable - partition management true *** FAILED *** (173 milliseconds)
  org.apache.spark.sql.AnalysisException: Path does not exist: file:/C:projectsspark	arget	mpspark-cd234a6d-9cb4-4d1d-9e51-854ae9543bbd;

- SPARK-18635 special chars in partition values - partition management true *** FAILED *** (2 seconds, 967 milliseconds)
  org.apache.spark.sql.AnalysisException: org.apache.hadoop.hive.ql.metadata.HiveException: MetaException(message:java.lang.IllegalArgumentException: Can not create a Path from an empty string);

- SPARK-18635 special chars in partition values - partition management false *** FAILED *** (62 milliseconds)
  org.apache.spark.sql.AnalysisException: org.apache.hadoop.hive.ql.metadata.HiveException: MetaException(message:java.lang.IllegalArgumentException: Can not create a Path from an empty string);

- SPARK-18659 insert overwrite table with lowercase - partition management true *** FAILED *** (63 milliseconds)
  org.apache.spark.sql.AnalysisException: org.apache.hadoop.hive.ql.metadata.HiveException: MetaException(message:java.lang.IllegalArgumentException: Can not create a Path from an empty string);

- SPARK-18544 append with saveAsTable - partition management false *** FAILED *** (266 milliseconds)
  org.apache.spark.sql.AnalysisException: org.apache.hadoop.hive.ql.metadata.HiveException: MetaException(message:java.lang.IllegalArgumentException: Can not create a Path from an empty string);

- SPARK-18659 insert overwrite table files - partition management false *** FAILED *** (63 milliseconds)
  org.apache.spark.sql.AnalysisException: org.apache.hadoop.hive.ql.metadata.HiveException: MetaException(message:java.lang.IllegalArgumentException: Can not create a Path from an empty string);

- SPARK-18659 insert overwrite table with lowercase - partition management false *** FAILED *** (78 milliseconds)
  org.apache.spark.sql.AnalysisException: org.apache.hadoop.hive.ql.metadata.HiveException: MetaException(message:java.lang.IllegalArgumentException: Can not create a Path from an empty string);

- sanity check table setup *** FAILED *** (31 milliseconds)
  org.apache.spark.sql.AnalysisException: org.apache.hadoop.hive.ql.metadata.HiveException: MetaException(message:java.lang.IllegalArgumentException: Can not create a Path from an empty string);

- insert into partial dynamic partitions *** FAILED *** (47 milliseconds)
  org.apache.spark.sql.AnalysisException: org.apache.hadoop.hive.ql.metadata.HiveException: MetaException(message:java.lang.IllegalArgumentException: Can not create a Path from an empty string);

- insert into fully dynamic partitions *** FAILED *** (62 milliseconds)
  org.apache.spark.sql.AnalysisException: org.apache.hadoop.hive.ql.metadata.HiveException: MetaException(message:java.lang.IllegalArgumentException: Can not create a Path from an empty string);

- insert into static partition *** FAILED *** (78 milliseconds)
  org.apache.spark.sql.AnalysisException: org.apache.hadoop.hive.ql.metadata.HiveException: MetaException(message:java.lang.IllegalArgumentException: Can not create a Path from an empty string);

- overwrite partial dynamic partitions *** FAILED *** (63 milliseconds)
  org.apache.spark.sql.AnalysisException: org.apache.hadoop.hive.ql.metadata.HiveException: MetaException(message:java.lang.IllegalArgumentException: Can not create a Path from an empty string);

- overwrite fully dynamic partitions *** FAILED *** (47 milliseconds)
  org.apache.spark.sql.AnalysisException: org.apache.hadoop.hive.ql.metadata.HiveException: MetaException(message:java.lang.IllegalArgumentException: Can not create a Path from an empty string);

- overwrite static partition *** FAILED *** (63 milliseconds)
  org.apache.spark.sql.AnalysisException: org.apache.hadoop.hive.ql.metadata.HiveException: MetaException(message:java.lang.IllegalArgumentException: Can not create a Path from an empty string);
```

```
MetastoreDataSourcesSuite:
- check change without refresh *** FAILED *** (203 milliseconds)
  org.apache.spark.sql.AnalysisException: Path does not exist: file:/C:projectsspark	arget	mpspark-00713fe4-ca04-448c-bfc7-6c5e9a2ad2a1;

- drop, change, recreate *** FAILED *** (78 milliseconds)
  org.apache.spark.sql.AnalysisException: Path does not exist: file:/C:projectsspark	arget	mpspark-2030a21b-7d67-4385-a65b-bb5e2bed4861;

- SPARK-15269 external data source table creation *** FAILED *** (78 milliseconds)
  org.apache.spark.sql.AnalysisException: Path does not exist: file:/C:projectsspark	arget	mpspark-4d50fd4a-14bc-41d6-9232-9554dd233f86;

- CTAS *** FAILED *** (109 milliseconds)
  java.lang.IllegalArgumentException: Can not create a Path from an empty string

- CTAS with IF NOT EXISTS *** FAILED *** (109 milliseconds)
  java.lang.IllegalArgumentException: Can not create a Path from an empty string

- CTAS: persisted partitioned bucketed data source table *** FAILED *** (0 milliseconds)
  java.lang.IllegalArgumentException: Can not create a Path from an empty string

- SPARK-15025: create datasource table with path with select *** FAILED *** (16 milliseconds)
  java.lang.IllegalArgumentException: Can not create a Path from an empty string

- CTAS: persisted partitioned data source table *** FAILED *** (47 milliseconds)
  java.lang.IllegalArgumentException: Can not create a Path from an empty string
```

```
HiveMetastoreCatalogSuite:
- Persist non-partitioned parquet relation into metastore as managed table using CTAS *** FAILED *** (16 milliseconds)
  java.lang.IllegalArgumentException: Can not create a Path from an empty string

- Persist non-partitioned orc relation into metastore as managed table using CTAS *** FAILED *** (16 milliseconds)
  java.lang.IllegalArgumentException: Can not create a Path from an empty string
```

```
HiveUDFSuite:
- SPARK-11522 select input_file_name from non-parquet table *** FAILED *** (16 milliseconds)
  org.apache.spark.sql.AnalysisException: org.apache.hadoop.hive.ql.metadata.HiveException: MetaException(message:java.lang.IllegalArgumentException: Can not create a Path from an empty string);
```

```
QueryPartitionSuite:
- SPARK-13709: reading partitioned Avro table with nested schema *** FAILED *** (250 milliseconds)
  org.apache.spark.sql.AnalysisException: org.apache.hadoop.hive.ql.metadata.HiveException: MetaException(message:java.lang.IllegalArgumentException: Can not create a Path from an empty string);
```

```
ParquetHiveCompatibilitySuite:
- simple primitives *** FAILED *** (16 milliseconds)
  org.apache.spark.sql.AnalysisException: org.apache.hadoop.hive.ql.metadata.HiveException: MetaException(message:java.lang.IllegalArgumentException: Can not create a Path from an empty string);

- SPARK-10177 timestamp *** FAILED *** (0 milliseconds)
  org.apache.spark.sql.AnalysisException: org.apache.hadoop.hive.ql.metadata.HiveException: MetaException(message:java.lang.IllegalArgumentException: Can not create a Path from an empty string);

- array *** FAILED *** (16 milliseconds)
  org.apache.spark.sql.AnalysisException: org.apache.hadoop.hive.ql.metadata.HiveException: MetaException(message:java.lang.IllegalArgumentException: Can not create a Path from an empty string);

- map *** FAILED *** (16 milliseconds)
  org.apache.spark.sql.AnalysisException: org.apache.hadoop.hive.ql.metadata.HiveException: MetaException(message:java.lang.IllegalArgumentException: Can not create a Path from an empty string);

- struct *** FAILED *** (0 milliseconds)
  org.apache.spark.sql.AnalysisException: org.apache.hadoop.hive.ql.metadata.HiveException: MetaException(message:java.lang.IllegalArgumentException: Can not create a Path from an empty string);

- SPARK-16344: array of struct with a single field named 'array_element' *** FAILED *** (15 milliseconds)
  org.apache.spark.sql.AnalysisException: org.apache.hadoop.hive.ql.metadata.HiveException: MetaException(message:java.lang.IllegalArgumentException: Can not create a Path from an empty string);
```

## How was this patch tested?

Manually tested via AppVeyor.

```
ColumnExpressionSuite:
- input_file_name, input_file_block_start, input_file_block_length - FileScanRDD (234 milliseconds)
- input_file_name, input_file_block_start, input_file_block_length - HadoopRDD (235 milliseconds)
- input_file_name, input_file_block_start, input_file_block_length - NewHadoopRDD (203 milliseconds)
```

```
DataStreamReaderWriterSuite:
- source metadataPath (63 milliseconds)
```

```
GlobalTempViewSuite:
 - CREATE GLOBAL TEMP VIEW USING (436 milliseconds)
```

```
CreateTableAsSelectSuite:
- CREATE TABLE USING AS SELECT (171 milliseconds)
- create a table, drop it and create another one with the same name (422 milliseconds)
- create table using as select - with partitioned by (141 milliseconds)
- create table using as select - with non-zero buckets (125 milliseconds)
```

```
HiveMetadataCacheSuite:
- partitioned table is cached when partition pruning is true (3 seconds, 211 milliseconds)
- partitioned table is cached when partition pruning is false (1 second, 781 milliseconds)
```

```
MultiDatabaseSuite:
 - createExternalTable() to non-default database - with USE (797 milliseconds)
 - createExternalTable() to non-default database - without USE (640 milliseconds)
 - invalid database name and table names (62 milliseconds)
```

```
OrcQuerySuite:
 - SPARK-8501: Avoids discovery schema from empty ORC files (703 milliseconds)
 - Verify the ORC conversion parameter: CONVERT_METASTORE_ORC (750 milliseconds)
 - converted ORC table supports resolving mixed case field (625 milliseconds)
```

```
HadoopFsRelationTest - JsonHadoopFsRelationSuite, OrcHadoopFsRelationSuite, ParquetHadoopFsRelationSuite, SimpleTextHadoopFsRelationSuite:
 - Locality support for FileScanRDD (296 milliseconds)
```

```
HiveQuerySuite:
 - CREATE TEMPORARY FUNCTION (125 milliseconds)
 - ADD FILE command (250 milliseconds)
 - ADD JAR command 2 (609 milliseconds)
```

```
PruneFileSourcePartitionsSuite:
- PruneFileSourcePartitions should not change the output of LogicalRelation (359 milliseconds)
```

```
HiveCommandSuite:
 - LOAD DATA LOCAL (1 second, 829 milliseconds)
 - LOAD DATA (1 second, 735 milliseconds)
 - Truncate Table (1 second, 641 milliseconds)
```

```
HiveExternalCatalogBackwardCompatibilitySuite:
 - make sure we can read table created by old version of Spark (32 milliseconds)
 - make sure we can alter table location created by old version of Spark (125 milliseconds)
 - make sure we can rename table created by old version of Spark (281 milliseconds)
```

```
ExternalCatalogSuite:
- create/drop/rename partitions should create/delete/rename the directory (625 milliseconds)
```

```
SQLQuerySuite:
- describe functions - temporary user defined functions (31 milliseconds)
- specifying database name for a temporary table is not allowed (390 milliseconds)
```

```
PartitionProviderCompatibilitySuite:
 - convert partition provider to hive with repair table (813 milliseconds)
 - when partition management is enabled, new tables have partition provider hive (562 milliseconds)
 - when partition management is disabled, new tables have no partition provider (344 milliseconds)
 - when partition management is disabled, we preserve the old behavior even for new tables (422 milliseconds)
 - insert overwrite partition of legacy datasource table (750 milliseconds)
 - SPARK-18544 append with saveAsTable - partition management true (985 milliseconds)
 - SPARK-18635 special chars in partition values - partition management true (3 seconds, 328 milliseconds)
 - SPARK-18635 special chars in partition values - partition management false (2 seconds, 891 milliseconds)
 - SPARK-18659 insert overwrite table with lowercase - partition management true (750 milliseconds)
 - SPARK-18544 append with saveAsTable - partition management false (656 milliseconds)
 - SPARK-18659 insert overwrite table files - partition management false (922 milliseconds)
 - SPARK-18659 insert overwrite table with lowercase - partition management false (469 milliseconds)
 - sanity check table setup (937 milliseconds)
 - insert into partial dynamic partitions (2 seconds, 985 milliseconds)
 - insert into fully dynamic partitions (1 second, 937 milliseconds)
 - insert into static partition (1 second, 578 milliseconds)
 - overwrite partial dynamic partitions (7 seconds, 561 milliseconds)
 - overwrite fully dynamic partitions (1 second, 766 milliseconds)
 - overwrite static partition (1 second, 797 milliseconds)
```

```
MetastoreDataSourcesSuite:
 - check change without refresh (610 milliseconds)
 - drop, change, recreate (437 milliseconds)
 - SPARK-15269 external data source table creation (297 milliseconds)
 - CTAS with IF NOT EXISTS (437 milliseconds)
 - CTAS: persisted partitioned bucketed data source table (422 milliseconds)
 - SPARK-15025: create datasource table with path with select (265 milliseconds)
 - CTAS (438 milliseconds)
 - CTAS with IF NOT EXISTS (469 milliseconds)
 - CTAS: persisted partitioned bucketed data source table (406 milliseconds)
```

```
HiveMetastoreCatalogSuite:
 - Persist non-partitioned parquet relation into metastore as managed table using CTAS (406 milliseconds)
 - Persist non-partitioned orc relation into metastore as managed table using CTAS (313 milliseconds)
```

```
HiveUDFSuite:
 - SPARK-11522 select input_file_name from non-parquet table (3 seconds, 144 milliseconds)
```

```
QueryPartitionSuite:
 - SPARK-13709: reading partitioned Avro table with nested schema (1 second, 67 milliseconds)
```

```
ParquetHiveCompatibilitySuite:
 - simple primitives (745 milliseconds)
 - SPARK-10177 timestamp (375 milliseconds)
 - array (407 milliseconds)
 - map (409 milliseconds)
 - struct (437 milliseconds)
 - SPARK-16344: array of struct with a single field named 'array_element' (391 milliseconds)
```

Author: hyukjinkwon <gurwls223@gmail.com>

Closes #16397 from HyukjinKwon/SPARK-18922-paths.