[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/build/mvn b/build/mvn
index 866bad892c..1e393c331d 100755
--- a/build/mvn
+++ b/build/mvn
@@ -22,7 +22,7 @@ _DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
 # Preserve the calling directory
 _CALLING_DIR="$(pwd)"
 # Options used during compilation
-_COMPILE_JVM_OPTS="-Xmx2g -XX:MaxPermSize=512M -XX:ReservedCodeCacheSize=512m"
+_COMPILE_JVM_OPTS="-Xmx2g -XX:ReservedCodeCacheSize=512m"
 
 # Installs any application tarball given a URL, the expected tarball name,
 # and, optionally, a checkable binary path to determine if the binary has
@@ -141,13 +141,9 @@ cd "${_CALLING_DIR}"
 # Now that zinc is ensured to be installed, check its status and, if its
 # not running or just installed, start it
 if [ -n "${ZINC_INSTALL_FLAG}" -o -z "`"${ZINC_BIN}" -status -port ${ZINC_PORT}`" ]; then
-  ZINC_JAVA_HOME=
-  if [ -n "$JAVA_7_HOME" ]; then
-    ZINC_JAVA_HOME="env JAVA_HOME=$JAVA_7_HOME"
-  fi
   export ZINC_OPTS=${ZINC_OPTS:-"$_COMPILE_JVM_OPTS"}
   "${ZINC_BIN}" -shutdown -port ${ZINC_PORT}
-  $ZINC_JAVA_HOME "${ZINC_BIN}" -start -port ${ZINC_PORT} \
+  "${ZINC_BIN}" -start -port ${ZINC_PORT} \
     -scala-compiler "${SCALA_COMPILER}" \
     -scala-library "${SCALA_LIBRARY}" &>/dev/null
 fi