code: public Postcard withParcelableArrayList(@Nullable String key, @Nullable ArrayList<? extends Parcelable> value) {
          mBundle.putParcelableArrayList(key, value);
          return this;
      }
docs: Inserts a List of Parcelable values into the mapping of this Bundle,
  replacing any existing value for the given key.  Either key or value may
  be null.
  
  @param key   a String, or null
  @param value an ArrayList of Parcelable objects, or null
  @return current