Bug 117493 [content assist] CompletionRequestor#completionFailure(IProblem)) is ignored
This got introduced after 3.2 M1 (i.e. broken in 3.2 M2 and newer). If completion fails we now always show: "No completion available." instead of the real error text. Example: for (Iterator i=things.iterator(); i.<ctrl-space> // Iterator not yet imported)
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/text/java/ContentAssistProcessor.java
* @param viewer the viewer that content assist is invoked on
	 * @param offset the content assist offset
	 * @return the context to be passed to the computers
	 */
	protected TextContentAssistInvocationContext createContext(ITextViewer viewer, int offset) {
		return new TextContentAssistInvocationContext(viewer, offset);
	}
	private List getCategories() {
		if (fCategoryIteration == null)
			return fCategories;
		
		int iteration= fRepetition % fCategoryIteration.size();
		fAssistant.setMessage(createIterationMessage());
		fAssistant.setEmptyMessage(createEmptyMessage());
		fRepetition++;
		
		return (List) fCategoryIteration.get(iteration);
	}
	private List getCategoryIteration() {
		List sequence= new ArrayList();
		sequence.add(getDefaultCategories());
		for (Iterator it= getSeparateCategories().iterator(); it.hasNext();) {
			CompletionProposalCategory cat= (CompletionProposalCategory) it.next();
			sequence.add(Collections.singletonList(cat));
		}
		return sequence;
	}
	private List getDefaultCategories() {
		
		List included= new ArrayList();