Java 9 Support

[gorkem]

Study and determine the tasks for Che to fully support Java 9

Issues reported by @benoitf at date of 16 october 2017:

compiling che with Java 9 blocker :

• Gwt and its maven plugin are not working with Java9
  need to update to HEAD-MASTER (2.8.2) and new gwt plugin
  Migrate to the new generation gwt-maven-plugin #6602

compiling issues with Java9 : plug-Ins errors with workarounds :

• error-prone is not handling Java9 for now (ok with newer version

  • JDK 9 support google/error-prone#448

• lot of maven plug-Ins need to be updated to their latest version to handle Java9 correctly

  • Remove deprecated single descriptor and move to multi descriptors which is the replacement #5490 Avoid deprecated configuration for maven assembly plugin

• tools.jar is referenced in debugger server (but tools.jar is gone with Java9)

• plexus-component-metadata needs to be updated as well https://github.com/eclipse/che/blob/513aa19ebd121093746209fcc4b31697b1424331/plugins/plugin-maven/maven-server/maven-server-impl/pom.xml#L214-L217

• eclipselink failures on Java9. Updating to EclipseLink 2.7.0 solves some issues

• Mockito failures on Java9. We should update to a recent version of Mockito (2.10 release)

  • mockito-all artifact is no longer existing
  • mockitong incompatible with Mockito 2.x (usage of removed annotations)

• gwt mockito is not working with Java9
  I've provided Make jdk.internal.reflect package being loaded by the standard classloader google/gwtmockito#73 but required to release a new version

• Lucene failures on Java9. Updating to Lucene 7.0.0 solves some issues (current=5.2.1)

• Usage of internal classes of JMX stuff

  • https://github.com/eclipse/che/blob/5b373e6cf5bfeb16f278c4d750fe64361445eeb4/core/che-core-api-core/src/main/java/org/eclipse/che/api/core/util/SystemInfo.java#L76-L79

• org.reflections and usage of Classpath (assuming that for example current classloader is a URLClassLoader is not working on Java9 as boot classloader is not anymore a URLClassLoader)

Runtime

• [ ]: wrong path of logging.properties in Tomcat
  http://tomcat.10.x6.nabble.com/svn-commit-r1809434-in-tomcat-trunk-java-org-apache-juli-ClassLoaderLogManager-java-webapps-docs-chal-td5067587.html

(fixed in new Tomcat release)

[TylerJewell]

Please move each of the issues into the main description, and then create sub-tasks for each item that we should pursue.

[gorkem]

@fbricon some more Java 9 stuff to follow up :)

[skabashnyuk]

Any idea how to deal with tools.jar is referenced in debugger server (but tools.jar is gone with Java9)?

[benoitf]

@skabashnyuk in my experiment I was able to compile debugger server without tools.jar (I kept tools.jar dependency only in a profile enabled on java 1.8)

[azatsarynnyy]

FYI in Che6 we don't depend on the legacy mojo's gwt-maven-plugin anymore (which is tightly linked to a specific version of GWT). GWT 2.8.2, which supports running in Java 9, is already released.

[benoitf]

@azatsarynnyy yep, I already filed CQs for GWT 2.8.2 https://dev.eclipse.org/ipzilla/show_bug.cgi?id=14599

[azatsarynnyy]

@benoitf thanks, I've added CQ link to the issue #6859

[benoitf]

gwt-maven-plugin has been released this week-end with the new 2.8.2 version

so now we can compile Che master 5.x with Java9 (skipping unit tests)

$ mvn -DskipTests=true -Dfindbugs.skip=true -Dgwt.compiler.localWorkers=2 -T 1C -Dgwt.compiler.enableClosureCompiler=false -Dskip-enforce -Dskip-validate-sources -Dversion.gwt.plugin=2.8.2 clean install

for Che 6.x we can as well by specifying GWT version
-Dcom.google.gwt.version=2.8.2

[benoitf]

I'm able to use GWT 2.8.2 + gwt mockito with a fix that I've provided upstream (google/gwtmockito#73)
--> need to wait gwt mockito 1.1.8

[benoitf]

gwt mockito released a new version including my fix.
It has been merged in che-dependencies repository
so now, Che6 branch can be compiled by using JDK 9 as it was the last missing PR

[slemeur]

Closing :

• The work needed to be done to be able to compile Che using JD9 has been completed.
• In order to provide Java9 support for end-users we will need Switch Java infrastructure to JDT LS #6157

[dmytro-ndp]

@slemeur: it has turned out recently that our automated functional tests don't support Java 9 (issue #8852).