code: public ClientConfig addLabel(String label) {
          Preconditions.isNotNull(label, "label");
          labels.add(label);
          return this;
      }
docs: Adds a label for this client {@link com.hazelcast.core.Client} available
  
  @param label The label to be added.
  @return configured {@link com.hazelcast.client.config.ClientConfig} for chaining