JDK 6 will reach the end of extended support in December 2018, you can read https://www.oracle.com/technetwork/java/javase/eol-135779.html for details.
As a result, set the minimum required Java version for Codehaus Cargo to Java 7:
Update Maven build settings
Update code style with the features introduced in Java 7
Rewrite the try - catch statements as try-with-resources statements: https://docs.oracle.com/javase/tutorial/essential/exceptions/tryResourceClose.html
Simplify handling of multiple exceptions: https://docs.oracle.com/javase/7/docs/technotes/guides/language/catch-multiple.html
Perhaps add Java 11 as that version is also LTS
Adding Java 11 means some of the integration tests (Daemon for example) will need to be updated so they use different container versions: org.apache.jasper.JasperException: PWC6033: Error in Javac compilation for JSP||PWC6199: Generated servlet error:|Source option 5 is no longer supported. Use 6 or later.||PWC6199: Generated servlet error:|Target option 1.5 is no longer supported. Use 1.6 or later. thrown by Jetty 7.6.21.v20160908.