Bug 14444 java editor refers to internal jcore classes
ClassFileEditor CompilationUnitDocumentProvider JavaMarkerAnnotation
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/javaeditor/CompilationUnitDocumentProvider.java
protected Position createPositionFromProblem(IProblem problem) {
				int start= problem.getSourceStart();
				if (start < 0)
					return null;
					
				int length= problem.getSourceEnd() - problem.getSourceStart() + 1;
				if (length < 0)
					return null;
					
				return new Position(start, length);
			}
			
			/*
			 * @see IProblemRequestor#beginReporting()
			 */
			public void beginReporting() {
				ICompilationUnit unit= getWorkingCopy(fInput);
				try {
					if (unit != null && unit.getJavaProject().isOnClasspath(unit))
						fCollectedProblems= new ArrayList();
					else
						fCollectedProblems= null;
				} catch (JavaModelException e) {
					fCollectedProblems= null;	
				}				
			}
			
			/*
			 * @see IProblemRequestor#acceptProblem(IProblem)
			 */