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/dialogs/StatusUtil.java
/**
	 * Applies the status to the status line of a dialog page.
	 */
	public static void applyToStatusLine(DialogPage page, IStatus status) {
		String message= status.getMessage();
		switch (status.getSeverity()) {
			case IStatus.OK:
				page.setErrorMessage(null);
				page.setMessage(message, DialogPage.NONE);
				break;
			case IStatus.WARNING:
				page.setErrorMessage(null);
				page.setMessage(message, DialogPage.WARNING);
				break;				
			case IStatus.INFO:
				page.setErrorMessage(null);
				page.setMessage(message, DialogPage.INFORMATION);
				break;			
			default:
				if (message.length() == 0) {
					message= null;
				}
				page.setErrorMessage(message);
				page.setMessage(null);
				break;		
		}
	}
}