A number of third-party libraries in the product are multi-version JARs, suited for use with Java 8 and Java 9. If you are obfuscating your application with Java 8, this may result in an error message: 

Can't process class [META-INF/versions/9/module-info.class] (Unsupported class version number [54.0] (maximum 52.0, Java 1.8))

To resolve this error, you need to filter the multi-version JARs.

The JAR filtering is illustrated in our bundled scripts. For example, deploy_samples.xml contains the line: 

<libraryjar filter="!META-INF/versions/**">