Bug 13034 Cannot create a Source Folder in a new Java Project
build 20020404 If you try and create a Source Folder in a Java Project you have just created you get an error preventing you from hitting finish. STEPS 1) Create Java Project Foo 2) Open New->Source Folder 3) Enter Bar as the name - you will get "Cannot nest entry Bar inside entry Foo/Bar" 4) Create a folder Bar. 5) Add it as a source folder in the Properties Dialog for Foo. No problem.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/wizards/NewSourceFolderWizardPage.java
return (dialog.open() == EditClassPathDialog.OK);
	}
	
	private IContainer[] getFilteredExistingContainerEntries() {
		if (fCurrJProject == null) {
			return new IContainer[0];
		}
		List res= new ArrayList();
		try {
			IResource container= fWorkspaceRoot.findMember(fCurrJProject.getOutputLocation());
			if (container != null) {
				res.add(container);
			}
		} catch (JavaModelException e) {
			JavaPlugin.log(e);
		}	
		
		for (int i= 0; i < fEntries.length; i++) {
			IClasspathEntry elem= fEntries[i];
			if (elem.getEntryKind() == IClasspathEntry.CPE_SOURCE) {
				IResource container= fWorkspaceRoot.findMember(elem.getPath());
				if (container != null) {
					res.add(container);
				}
			}		
		}
		return (IContainer[]) res.toArray(new IContainer[res.size()]);
	}	
		
}