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
*/
	protected void disposeFileInfo(Object element, FileInfo info) {
		if (info instanceof CompilationUnitInfo) {
			CompilationUnitInfo cuInfo= (CompilationUnitInfo) info;
			try  {
			    cuInfo.fCopy.discardWorkingCopy();
			} catch (JavaModelException x)  {
			    handleCoreException(x, x.getMessage());
			}
			if (cuInfo.fModel != null)
				cuInfo.fModel.removeAnnotationModelListener(fGlobalAnnotationModelListener);
		}
		super.disposeFileInfo(element, info);
	}
	
	/*
	 * @see org.eclipse.ui.editors.text.TextFileDocumentProvider#connect(java.lang.Object)
	 * @since 3.2
	 */
	public void connect(Object element) throws CoreException {
		super.connect(element);
		if (getFileInfo(element) != null)
			return;
		CompilationUnitInfo info= (CompilationUnitInfo)fFakeCUInfoMap.get(element);
		if (info == null) {
			ICompilationUnit cu= createFakeCompiltationUnit(element, true);
			if (cu == null)
				return;
			info= new CompilationUnitInfo();
			info.fCopy= cu;