code: @SuppressWarnings("unchecked")
      protected String addeDependency(Appliable<? extends Indexable> appliable) {
          TaskGroup.HasTaskGroup dependency = (TaskGroup.HasTaskGroup) appliable;
          return this.addDependency(dependency);
      }
docs: Add an appliable dependency for this task item.
  
  @param appliable the appliable dependency.
  @return the key to be used as parameter to taskResult(string) method to retrieve updated dependency