Investigate refactorings for Java 1.9

[JnRouvignac]

• JDK9 is hiding several internal APIs, here is a list of replacements for the most commonly used APIs:
  • https://wiki.openjdk.java.net/display/JDK8/Java+Dependency+Analysis+Tool
• List.of(), Set.of(), Map.of() can provide significant memory savings and are immutable
  • See Collections Refueled talk at JavaOne 2016

[Fabrice-TIERCELIN]

~~To create refactorings for Java 1.9, Java 9 first needs to be supported by JDT Core. It is supported from 4.4.1:~~ ~~https://bugs.eclipse.org/bugs/show_bug.cgi?id=457413~~

~~But JDT Core 4.4.1 is not yet available:~~ ~~https://mvnrepository.com/artifact/org.eclipse.jdt/org.eclipse.jdt.core~~