[MINOR] Added import to fix compilation

[tdas]

What changes were proposed in this pull request?

Two back to PRs implicitly conflicted by one PR removing an existing import that the other PR needed. This did not cause explicit conflict as the import already existed, but not used.

https://amplab.cs.berkeley.edu/jenkins/view/Spark%20QA%20Compile/job/spark-master-compile-maven-hadoop-2.7/8226/consoleFull

[info] Compiling 342 Scala sources and 97 Java sources to /home/jenkins/workspace/spark-master-compile-maven-hadoop-2.7/sql/core/target/scala-2.11/classes...
[warn] /home/jenkins/workspace/spark-master-compile-maven-hadoop-2.7/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/parquet/ParquetFileFormat.scala:128: value ENABLE_JOB_SUMMARY in object ParquetOutputFormat is deprecated: see corresponding Javadoc for more information.
[warn]       && conf.get(ParquetOutputFormat.ENABLE_JOB_SUMMARY) == null) {
[warn]                                       ^
[error] /home/jenkins/workspace/spark-master-compile-maven-hadoop-2.7/sql/core/src/main/scala/org/apache/spark/sql/execution/streaming/statefulOperators.scala:95: value asJava is not a member of scala.collection.immutable.Map[String,Long]
[error]       new java.util.HashMap(customMetrics.mapValues(long2Long).asJava)
[error]                                                                ^
[warn] one warning found
[error] one error found
[error] Compile failed at Aug 21, 2018 4:04:35 PM [12.827s]

How was this patch tested?

It compiles!

[SparkQA]

Test build #95058 has finished for PR 22175 at commit d540d5a.

• This patch fails some tests.
• This patch merges cleanly.
• This patch adds no public classes.

[tdas]

jenkins retest this please

[gatorsmile]

LGTM!

[tdas]

Merged as compilation passed.

[HeartSaVioR]

Didn't notice this PR. Thanks for the quick turnaround!

[SparkQA]

Test build #95059 has finished for PR 22175 at commit f40c600.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds no public classes.