code: @CheckForNull
      public Descriptor<T> findByName(String id) {
          for (Descriptor<T> d : this)
              if(d.getId().equals(id))
                  return d;
          return null;
      }
docs: Finds a descriptor by their {@link Descriptor#getId()}.
  @param id Descriptor ID
  @return If none is found, {@code null} is returned.