Herman van Hovell
authored
## What changes were proposed in this pull request? This is absolutely minor. PR https://github.com/apache/spark/pull/15595 uses `dt1.asNullable == dt2.asNullable` expressions in a few places. It is however more efficient to call `dt1.sameType(dt2)`. I have replaced every instance of the first pattern with the second pattern (3/5 were introduced by #15595). ## How was this patch tested? Existing tests. Author: Herman van Hovell <hvanhovell@databricks.com> Closes #16041 from hvanhovell/SPARK-18058. (cherry picked from commit d449988b) Signed-off-by:Reynold Xin <rxin@databricks.com>