Bug 75711 AstProvider should not create AST if requested by SelectionListenerWithASTManager
3.1 M2 If SelectionListenerWithASTManager waits for an AST and the editor closes we should not create an AST for that one but return null instead.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/javaeditor/ClipboardOperationAction.java
SimpleName curr= (SimpleName) res.get(i);
			IBinding binding= curr.resolveBinding();
			if (binding != null && binding.getKind() == IBinding.TYPE) {
				ITypeBinding typeBinding= (ITypeBinding) binding;
				if (typeBinding.isArray()) {
					typeBinding= typeBinding.getElementType();
				}
				if (typeBinding.isMember() || typeBinding.isTopLevel()) {
					String name= typeBinding.getQualifiedName();
					if (name.length() > 0) {
						namesToImport.add(name);
					}
				}
			}
		}
		if (namesToImport.isEmpty()) {
			return null;
		}
		
		return new ClipboardData(inputElement, (String[]) namesToImport.toArray(new String[namesToImport.size()]));
	}
	private void doPasteWithImportsOperation() {
		ITextEditor editor= getTextEditor();
		IJavaElement inputElement= (IJavaElement) editor.getEditorInput().getAdapter(IJavaElement.class);
		Clipboard clipboard= new Clipboard(getDisplay());
		ClipboardData importsData= (ClipboardData) clipboard.getContents(fgTransferInstance);
		if (importsData != null && inputElement instanceof ICompilationUnit && !importsData.isFromSame(inputElement)) {
			
			IRewriteTarget target= editor != null ? (IRewriteTarget) editor.getAdapter(IRewriteTarget.class) : null;
			if (target != null) {