code: public Optional<Label> show(String key)
      {
          Optional<Label> ret = Optional.absent();
          Collection<Label> labels = list();
          for(Label label : labels)
          {
              if(label.getKey().equals(key))
                  ret = Optional.of(label);
          }
          return ret;
      }
docs: Returns the label with the given key.
  <P>
  This is needed because the API does not contain an operation to get a label using the key directly.
  @param key The key of the label to return
  @return The label