code: public CDACallback<Transformed> one(String id, CDACallback<Transformed> callback) {
      return Callbacks.subscribeAsync(
          baseQuery()
              .one(id)
              .filter(new Predicate<CDAEntry>() {
                @Override
                public boolean test(CDAEntry entry) {
                  return entry.contentType().id().equals(contentTypeId);
                }
              })
              .map(this::transform),
          callback,
          client);
    }
docs: Retrieve the transformed entry from Contentful by using the given callback.
  
  @param id the id of the entry of type transformed.
  @return the input callback for chaining.
  @throws CDAResourceNotFoundException if no such resource was found.
  @throws IllegalStateException        if the transformed class could not be created.
  @throws IllegalStateException        if the transformed class could not be accessed.