code: public static IndexableTaskItem create(final FunctionalTaskItem taskItem) {
          return new IndexableTaskItem() {
              @Override
              protected Observable<Indexable> invokeTaskAsync(TaskGroup.InvocationContext context) {
                  FunctionalTaskItem.Context fContext = new FunctionalTaskItem.Context(this);
                  fContext.setInnerContext(context);
                  return taskItem.call(fContext);
              }
          };
      }
docs: Creates an IndexableTaskItem from provided FunctionalTaskItem.
  
  @param taskItem functional TaskItem
  @return IndexableTaskItem