[SPARK-21253][CORE][HOTFIX] Fix Scala 2.10 build

## What changes were proposed in this pull request?

A follow up PR to fix Scala 2.10 build for #18472

## How was this patch tested?

Jenkins

Author: Shixiong Zhu <shixiong@databricks.com>

Closes #18478 from zsxwing/SPARK-21253-2.