fix travis build (#16288)

Author: wing328

.travis.yml

@@ -136,7 +136,7 @@ script:
   # run integration tests defined in maven pom.xml
   # WARN: Travis will timeout after 10 minutes of no stdout/stderr activity, which is problematic with mvn --quiet.
   # show "error" only to reduce the log size
-  - ./mvnw -e --no-snapshot-updates --quiet --batch-mode --show-version clean install -DskipTests -Dmaven.javadoc.skip=true -Dorg.slf4j.simpleLogger.defaultLogLevel=error 2>&1 | grep -i error
+  - ./mvnw -e --no-snapshot-updates --quiet --batch-mode --show-version clean install -DskipTests -Dmaven.javadoc.skip=true -Dorg.slf4j.simpleLogger.defaultLogLevel=error
 after_success:
   # push to maven repo
   - if [ $SONATYPE_USERNAME ] && [ "$TRAVIS_PULL_REQUEST" == "false" ]; then