Bug 54900 [rulers] Java Editor does not show ruler on external Java files
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/javaeditor/CompilationUnitDocumentProvider.java
* @see Annotation#paint
			 */
			public void paint(GC gc, Canvas canvas, Rectangle r) {
				initializeImages();
				if (fImage != null)
					ImageUtilities.drawImage(fImage, gc, canvas, r, SWT.CENTER, SWT.TOP);
			}
			/*
			 * @see IJavaAnnotation#getImage(Display)
			 */
			public Image getImage(Display display) {
				initializeImages();
				return fImage;
			}
			/*
			 * @see IJavaAnnotation#getMessage()
			 */
			public String getText() {
				return fProblem.getMessage();
			}
			/*
			 * @see IJavaAnnotation#getArguments()
			 */
			public String[] getArguments() {
				return isProblem() ? fProblem.getArguments() : null;
			}
			/*
			 * @see IJavaAnnotation#getId()
			 */
			public int getId() {