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/CompletionProposalComputerDescriptor.java
for (int i= 0; i < children.length; i++) {
				String type= children[i].getAttributeAsIs(TYPE);
				checkNotNull(type, TYPE);
				partitions.add(type);
			}
			fPartitions= Collections.unmodifiableSet(partitions);
		}
		
		String activateAttribute= element.getAttributeAsIs(ACTIVATE);
		fActivate= Boolean.valueOf(activateAttribute).booleanValue();
		fClass= element.getAttributeAsIs(CLASS);
		checkNotNull(fClass, CLASS);
		
		String categoryId= element.getAttributeAsIs(CATEGORY_ID);
		if (categoryId == null)
			categoryId= DEFAULT_CATEGORY_ID;
		CompletionProposalCategory category= null;
		for (Iterator it= categories.iterator(); it.hasNext();) {
			CompletionProposalCategory cat= (CompletionProposalCategory) it.next();
			if (cat.getId().equals(categoryId)) {
				category= cat;
				break;
			}
		}
		if (category == null) {
			
			fCategory= new CompletionProposalCategory(categoryId, fName, registry);
			categories.add(fCategory);
		} else {
			fCategory= category;