Updated .travis.yml to build with the minimum and the latest JDKs

- Building with both the Oracle JDK and OpenJDK versions.

Author: emxsys

.travis.yml

@@ -4,12 +4,14 @@
 # Set up to run the Java build script per the Travis CI documentation
 language: java
 
-# Configure the build to use Oracle JDKs and Open JDKs
+# Configure the build to using the minimum and the latest Oracle JDKs and Open JDKs
 jdk:
   - openjdk8
   - openjdk11
+  - openjdk-ea
   - oraclejdk8
   - oraclejdk11
+  - oraclejdk-ea
 
 # Install the Ant JUnit package, which is missing from the Travis CI environment. See the Travis documentation: https://docs.travis-ci.com/user/installing-dependencies/#Adding-APT-Packages
 addons: