Correctly setup classpath/dependencies and fix checkstyle task that was partly broken because delayed setup of Java9 sourcesets. This also cleans packaging of META-INF. It also prepares forbiddenapis 2.6 upgrade
relates #29292
* Begin moving XContent to a separate lib/artifact
This commit moves a large portion of the XContent code from the `server` project
to the `libs/xcontent` project. For the pieces that have been moved, some
helpers have been duplicated to allow them to be decoupled from ES helper
classes. In addition, `Booleans` and `CheckedFunction` have been moved to the
`elasticsearch-core` project.
This decoupling is a move so that we can eventually make things like the
high-level REST client not rely on the entire ES jar, only the parts it needs.
There are some pieces that are still not decoupled, in particular some of the
XContent tests still remain in the server project, this is because they test a
large portion of the pluggable xcontent pieces through
`XContentElasticsearchException`. They may be decoupled in future work.
Additionally, there may be more piecese that we want to move to the xcontent lib
in the future that are not part of this PR, this is a starting point.
Relates to #28504
This commit introduces the ability for the core Elasticsearch JAR to be
a multi-release JAR containing code that is compiled for JDK 8 and code
that is compiled for JDK 9. At runtime, a JDK 8 JVM will ignore the JDK
9 compiled classfiles, and a JDK 9 JVM will use the JDK 9 compiled
classfiles instead of the JDK 8 compiled classfiles. With this work, we
utilize the new JDK 9 API for obtaining the PID of the running JVM,
instead of relying on a hack.
For now, we want to keep IDEs on JDK 8 so when the build is in an IDE we
ignore the JDK 9 source set (as otherwise the IDE would give compilation
errors). However, with this change, running Gradle from the command-line
now requires JAVA_HOME and JAVA_9_HOME to be set. This will require
follow-up work in our CI infrastructure and our release builds to
accommodate this change.
Relates #28051
This is related to #27933. It introduces a jar named elasticsearch-core
in the lib directory. This commit moves the JarHell class from server to
elasticsearch-core. Additionally, PathUtils and some of Loggers are
moved as JarHell depends on them.
Uwe Schindler
Adrien Grand
Lee Hinman
Ke Li
Jason Tedor
Alexander Reelsen
Tim Brooks