code: @NonNull
      public Transition removeTarget(@Nullable String targetName) {
          if (targetName != null && mTargetNames != null) {
              mTargetNames.remove(targetName);
          }
          return this;
      }
docs: Removes the given targetName from the list of transitionNames that this Transition
  is interested in animating.
  
  @param targetName The transitionName of a target view, must not be null.
  @return The Transition from which the targetName is removed.
  Returning the same object makes it easier to chain calls during
  construction, such as
  <code>transitionSet.addTransitions(new Fade()).removeTargetName(someName);</code>