Handle JRE container when adding module class path info in Java search

[trancexpress]

Handle JRE container when adding module class path info in Java search

[trancexpress]

The build path page decides the JRE is on the module path with this stack trace:

"main" #1 prio=6 os_prio=0 cpu=7618.77ms elapsed=2454.16s tid=0x00007f6560015440 nid=0x3e19 runnable  [0x00007f65647fc000]
   java.lang.Thread.State: RUNNABLE
        at org.eclipse.jdt.internal.ui.wizards.buildpaths.CPListElement.addModuleNodes(CPListElement.java:214)
        at org.eclipse.jdt.internal.ui.wizards.buildpaths.CPListElement.<init>(CPListElement.java:178)
        at org.eclipse.jdt.internal.ui.wizards.buildpaths.CPListElement.create(CPListElement.java:772)
        at org.eclipse.jdt.internal.ui.wizards.buildpaths.CPListElement.create(CPListElement.java:710)
        at org.eclipse.jdt.internal.ui.wizards.buildpaths.BuildPathsBlock.getCPListElements(BuildPathsBlock.java:446)
        at org.eclipse.jdt.internal.ui.wizards.buildpaths.BuildPathsBlock.init(BuildPathsBlock.java:341)
        at org.eclipse.jdt.internal.ui.preferences.BuildPathsPropertyPage.createWithJava(BuildPathsPropertyPage.java:170)
        at org.eclipse.jdt.internal.ui.preferences.BuildPathsPropertyPage.createContents(BuildPathsPropertyPage.java:88)
        at org.eclipse.jface.preference.PreferencePage.createControl(PreferencePage.java:244)
        at org.eclipse.jdt.internal.ui.preferences.BuildPathsPropertyPage.createControl(BuildPathsPropertyPage.java:99)
        at org.eclipse.jface.preference.PreferenceDialog.createPageControl(PreferenceDialog.java:1434)
        at org.eclipse.jface.preference.PreferenceDialog$8.run(PreferenceDialog.java:1197)

With this code:

	private boolean addModuleNodes(IClasspathEntry containerEntry, IClasspathEntry pseudoEntry) {
		boolean modulesAdded= false;
		if (containerEntry != null) {
			IPackageFragmentRoot[] fragmentRoots= fProject.findPackageFragmentRoots(containerEntry);
			if (fragmentRoots != null) {
				// detect if system library:
				boolean addChildren= false;
				if (fragmentRoots.length > 0) {
					IModuleDescription module= fragmentRoots[0].getModuleDescription();
					if (module != null && module.isSystemModule())
						addChildren= true;

isSystemModule() is implemented here: org.eclipse.jdt.internal.core.BinaryModule.isSystemModule():

	@Override
	public boolean isSystemModule() {
		IPackageFragmentRoot pfr = (IPackageFragmentRoot) getAncestor(IJavaElement.PACKAGE_FRAGMENT_ROOT);
		return pfr instanceof JrtPackageFragmentRoot;
	}
	@Overri

I guess we can add code like that in JavaSearchNameEnvironment.

It would be good to know where the compiler does this as well, since the compiler also adds the JRE on the module path... Likely its done with the instanceof JrtPackageFragmentRoot statements in org.eclipse.jdt.internal.core.SearchableEnvironment.