Support javaExtensions

[BoykoAlex]

VSCode has support RedHat Java LS extensions/plugins: https://github.com/redhat-developer/vscode-java/wiki/Contribute-a-Java-Extension
This needs to be mirrored in Atom because the LS is the same I think.

[damieng]

How can I try this out?

[BoykoAlex]

We are working on the extension for RedHat Java LS to get classpath from JDT instead of calculating it ourselves with maven API...
We haven't tried it with Atom yet, but will try it out very soon. This is just some preparation work to see whether this patch looks acceptable. Ideally it should work since the only thing required is absolute path to jars in the init message. I'll post how to test it once we get closer to the completion of our Java LS extension

[damieng]

Feels weird to build a new collection from inside a forEach... In C# I would have just done a SelectMany here and returned the collection that way.

[BoykoAlex]

It does :-) but there is no flatMap() in JS6... would have to improvise with map() and reduce()

[BoykoAlex]

This is how it'd look like:

  collectJavaExtensions() {
    return atom.packages.getLoadedPackages()
        .filter(pkg => Array.isArray(pkg.metadata.javaExtensions))
        .map(pkg => pkg.metadata.javaExtensions.map(p => path.resolve(pkg.path, p)))
        .reduce(e => e.concat([]));
  }

[damieng]

That looks good - functional FTW :)

[damieng]

Thanks! I'll mark this as 'experimental' in the CHANGELOG until we've proven it with the other side of the equation (the extension packages).

[BoykoAlex]

@damieng thank you!-)