[SPARK-19550][BUILD][CORE][WIP] Remove Java 7 support

- Move external/java8-tests tests into core, streaming, sql and remove
- Remove MaxPermGen and related options
- Fix some reflection / TODOs around Java 8+ methods
- Update doc references to 1.7/1.8 differences
- Remove Java 7/8 related build profiles
- Update some plugins for better Java 8 compatibility
- Fix a few Java-related warnings

For the future:

- Update Java 8 examples to fully use Java 8
- Update Java tests to use lambdas for simplicity
- Update Java internal implementations to use lambdas

## How was this patch tested?

Existing tests

Author: Sean Owen <sowen@cloudera.com>

Closes #16871 from srowen/SPARK-19493.

1 files changed, 1 insertions, 2 deletions

diff --git a/external/kafka-0-10-sql/src/main/scala/org/apache/spark/sql/kafka010/KafkaSource.scala b/external/kafka-0-10-sql/src/main/scala/org/apache/spark/sql/kafka010/KafkaSource.scala
index 02b23111af..9c5dceca2d 100644
--- a/external/kafka-0-10-sql/src/main/scala/org/apache/spark/sql/kafka010/KafkaSource.scala
+++ b/external/kafka-0-10-sql/src/main/scala/org/apache/spark/sql/kafka010/KafkaSource.scala
@@ -259,7 +259,7 @@ private[kafka010] class KafkaSource(
       val preferredLoc = if (numExecutors > 0) {
         // This allows cached KafkaConsumers in the executors to be re-used to read the same
         // partition in every batch.
-        Some(sortedExecutors(floorMod(tp.hashCode, numExecutors)))
+        Some(sortedExecutors(Math.floorMod(tp.hashCode, numExecutors)))
       } else None
       KafkaSourceRDDOffsetRange(tp, fromOffset, untilOffset, preferredLoc)
     }.filter { range =>
@@ -347,5 +347,4 @@ private[kafka010] object KafkaSource {
     if (a.host == b.host) { a.executorId > b.executorId } else { a.host > b.host }
   }
 
-  def floorMod(a: Long, b: Int): Int = ((a % b).toInt + b) % b
 }