code: @NonNull
      public ObservableDataBuilder<T> contentEquality(@Nullable EqualityFunction<? super T> contentEqualityFunction) {
          mContentEqualityFunction = contentEqualityFunction;
          return this;
      }
docs: Defines the function for evaluating whether two objects have the same contents, for the purpose of determining
  notifications.
  <p>
  By default, content equality is evaluated using {@link Object#equals(Object)}.