Update Travis build with more JDKs.
diff --git a/.travis.yml b/.travis.yml
index 605a9a8..51acb5e 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,24 +1,27 @@
-# Licensed to the Apache Software Foundation (ASF) under one or more
-# contributor license agreements. See the NOTICE file distributed with
-# this work for additional information regarding copyright ownership.
-# The ASF licenses this file to You under the Apache License, Version 2.0
-# (the "License"); you may not use this file except in compliance with
-# the License. You may obtain a copy of the License at
-#
-# http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
-
-language: java
-sudo: false
-
-jdk:
- - openjdk8
- - oraclejdk8
-
-after_success:
- - mvn -Ddoclint:none clean cobertura:cobertura coveralls:report
+# Licensed to the Apache Software Foundation (ASF) under one or more
+# contributor license agreements. See the NOTICE file distributed with
+# this work for additional information regarding copyright ownership.
+# The ASF licenses this file to You under the Apache License, Version 2.0
+# (the "License"); you may not use this file except in compliance with
+# the License. You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+language: java
+sudo: false
+
+jdk:
+ - oraclejdk8
+ - oraclejdk11
+ - openjdk8
+ - openjdk11
+ - openjdk-ea
+
+after_success:
+ - mvn -Ddoclint:none clean cobertura:cobertura coveralls:report
