code: public <T extends CDAResource> ObserveQuery<T> observe(Class<T> type) {
      return new ObserveQuery<>(type, this);
    }
docs: Returns an {@link ObserveQuery} for a given {@code type}, which can be used to return
  an {@link Flowable} that fetches the desired resources.
  
  @param type resource type. This can be either a {@link CDALocale}, a {@link CDAEntry},
  a {@link CDAAsset}, or a {@link CDAContentType}
  @param <T>  type for avoiding casting on calling side.
  @return A query to call {@link ObserveQuery#all()} or {@link ObserveQuery#one(String)} on it.
  @see #observeSpace()