Change Maven size (#518)

Author: lesv

.travis.yml

@@ -43,7 +43,7 @@ before_install:
   && set +x && source secrets.env && set -x
   || true
 - export GOOGLE_CLOUD_PROJECT=java-docs-samples-tests
-- export MAVEN_OPTS='-Xmx768m -XX:MaxPermSize=256m'
+- export MAVEN_OPTS='-Xmx2048m -XX:+ -XX:+PrintFlagsFinal'
 # Skip the install step, since Maven will download the dependencies we need
 # when the test build runs.
 # http://stackoverflow.com/q/31945809/101923