Bug 63898 [reconciling] Multiple threads calling IJavaReconcilingListener#reconciled() at the same time
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/javaeditor/CompilationUnitEditor.java
/*
		 * @see org.eclipse.jdt.internal.ui.text.link.LinkedPositionUI.ExitPolicy#doExit(org.eclipse.jdt.internal.ui.text.link.LinkedPositionManager, org.eclipse.swt.events.VerifyEvent, int, int)
		 */
		public ExitFlags doExit(LinkedModeModel model, VerifyEvent event, int offset, int length) {
			
			if (event.character == fExitCharacter) {
				
				if (fSize == fStack.size() && !isMasked(offset)) {
					BracketLevel level= (BracketLevel) fStack.peek();
					if (level.fFirstPosition.offset > offset || level.fSecondPosition.offset < offset)
						return null;
					if (level.fSecondPosition.offset == offset && length == 0)
						
						return new ExitFlags(ILinkedModeListener.UPDATE_CARET, false);
				}
			}
			return null;
		}
			
		private boolean isMasked(int offset) {
			IDocument document= getSourceViewer().getDocument();
			try {
				return fEscapeCharacter == document.getChar(offset - 1);
			} catch (BadLocationException e) {
			}
			return false;
		}
	}
	
	private static class BracketLevel {