public JibContainerBuilder addLabel(String key, String value) {
    containerBuildPlanBuilder.addLabel(key, value);
    containerConfigurationBuilder.addLabel(key, value);
    return this;
  }
Sets a label for the container.

@param key the label key
@param value the label value
@return this
jib-core/src/main/java/com/google/cloud/tools/jib/api/JibContainerBuilder.java