Infer the source root only when necessary

[jdneo]

• only infer the source root when the opened Java source file belongs
  to an unmanaged folder.

Signed-off-by: Sheng Chen [email protected]

[jdneo]

This PR temporarily avoids conflicts between different kind of invisible projects (e.g. unmanaged folder & JBang script)

Once the unmanaged folder has its own nature id, we can do a more accurate check.

[rgrunber]

Made a comment at redhat-developer/vscode-java#2552 (comment) since this patch doesn't fix the issue there. It seemed to me like the problem wasn't with JDT-LS so just want to verify that this change is necessary.

[jdneo]

Hi @rgrunber,

This PR is not aimed to fix redhat-developer/vscode-java#2552.

Since now we will increasingly infer the source root of the unmanaged folder when user opens a new java file. This PR is to skip the inference when the java file already belongs to other invisible kind projects (e.g. a JBang project).

[rgrunber]

The change makes sense then.

It's certainly true that our unmanaged (invisble) project has a single nature, which is org.eclipse.jdt.core.javanature .

Other unmanaged project types (eg. jbang) should define their own for in addition, or in place of that.

[jdneo]

And once #2182 is ready, we can make more accurate checks. I'll play around that change to see if it will break anything.