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/buildpaths/BuildPathsBlock.java
IStatus status= JavaConventions.validateClasspath(fCurrJProject, entries, path);
		if (!status.isOK()) {
			fBuildPathStatus.setError(status.getMessage());
			return;
		}
		if (res != null && res.exists() && fCurrJProject.exists()) {
			try {
				IPath oldOutputLocation= fCurrJProject.getOutputLocation();
				if (!oldOutputLocation.equals(fOutputLocationPath)) {
					if (((IContainer)res).members().length > 0) {
						fBuildPathStatus.setWarning(NewWizardMessages.getString("BuildPathsBlock.warning.OutputFolderNotEmpty")); 
						return;
					}
				}
			} catch (CoreException e) {
				JavaPlugin.log(e);
			}
		}
				
		fBuildPathStatus.setOK();
	}
	
	
	
	/**
	 * Creates a runnable that sets the configured build paths.
	 */
	public IRunnableWithProgress getRunnable(final IRemoveOldBinariesQuery reorgQuery) {
		final List classPathEntries= fClassPathList.getElements();