Bug 75711 AstProvider should not create AST if requested by SelectionListenerWithASTManager
3.1 M2 If SelectionListenerWithASTManager waits for an AST and the editor closes we should not create an AST for that one but return null instead.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/javaeditor/OverrideIndicatorManager.java
/**
	 * Overwrite and override indicator annotation.
	 * 
	 * @since 3.0
	 */
	class OverrideIndicator extends Annotation {
		
		private boolean fIsOverwriteIndicator;
		private String fAstNodeKey;
		
		/**
		 * Creates a new override annotation.
		 * 
		 * @param isOverwriteIndicator <code>true</code> if this annotation is
		 *            an overwrite indicator, <code>false</code> otherwise
		 * @param text the text associated with this annotation
		 * @param key the method binding key
		 * @since 3.0
		 */