Set Java/Buck version on plugin Buck build

Change-Id: Ief2f48550e6966c9695f4628e237d7e65fd9374b
diff --git a/jenkins/gerrit-buck-build-its-plugin.sh b/jenkins/gerrit-buck-build-its-plugin.sh
index 69791c5..d4b6c77 100644
--- a/jenkins/gerrit-buck-build-its-plugin.sh
+++ b/jenkins/gerrit-buck-build-its-plugin.sh
@@ -14,6 +14,10 @@
 git read-tree -u --prefix=plugins/its-base base/{branch}
 
 rm -Rf buck-out
+
+SOURCE_LEVEL=$(grep "source_level" .buckconfig || echo "source_level=7")
+. set-java.sh $(echo $SOURCE_LEVEL | cut -d '=' -f 2 | tr -d '[[:space:]]')
+
 buck build -v 3 plugins/its-{name}
 
 # Extract version information
diff --git a/jenkins/gerrit-buck-build-plugin-manual.sh b/jenkins/gerrit-buck-build-plugin-manual.sh
index 9c60427..4f8933f 100644
--- a/jenkins/gerrit-buck-build-plugin-manual.sh
+++ b/jenkins/gerrit-buck-build-plugin-manual.sh
@@ -14,6 +14,9 @@
 
 TARGETS=$(echo "{targets}" | sed -e 's/{{name}}/{name}/g')
 
+SOURCE_LEVEL=$(grep "source_level" .buckconfig || echo "source_level=7")
+. set-java.sh $(echo $SOURCE_LEVEL | cut -d '=' -f 2 | tr -d '[[:space:]]')
+
 buck build -v 3 $TARGETS
 
 for JAR in $(buck targets --show_output $TARGETS | awk '{{print $2}}')