[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, 2 insertions, 6 deletions

diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/types/Decimal.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/types/Decimal.scala
index 465fb83669..089c84d5f7 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/types/Decimal.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/types/Decimal.scala
@@ -134,12 +134,8 @@ final class Decimal extends Ordered[Decimal] with Serializable {
    * Set this Decimal to the given BigInteger value. Will have precision 38 and scale 0.
    */
   def set(bigintval: BigInteger): Decimal = {
-    // TODO: Remove this once we migrate to java8 and use longValueExact() instead.
-    require(
-      bigintval.compareTo(LONG_MAX_BIG_INT) <= 0 && bigintval.compareTo(LONG_MIN_BIG_INT) >= 0,
-      s"BigInteger $bigintval too large for decimal")
     this.decimalVal = null
-    this.longVal = bigintval.longValue()
+    this.longVal = bigintval.longValueExact()
     this._precision = DecimalType.MAX_PRECISION
     this._scale = 0
     this
@@ -178,7 +174,7 @@ final class Decimal extends Ordered[Decimal] with Serializable {
 
   def toUnscaledLong: Long = {
     if (decimalVal.ne(null)) {
-      decimalVal.underlying().unscaledValue().longValue()
+      decimalVal.underlying().unscaledValue().longValueExact()
     } else {
       longVal
     }