docs: public Flowable<Transformed> one(String id) {
      try {
        return baseQuery()
            .one(id)
            .filter(new Predicate<CDAEntry>() {
              @Override
              public boolean test(CDAEntry entry) {
                return entry.contentType().id()
                    .equals(contentTypeId);
              }
            })
            .map(new Function<CDAEntry, Transformed>() {
              @Override
              public Transformed apply(CDAEntry entry) throws Exception {
                return TransformQuery.this.transform(entry);
              }
            });
      } catch (NullPointerException e) {
        throw new CDAResourceNotFoundException(CDAEntry.class, id);
      }
    }