public Builder entity(Entity entity){
  if (entities == null) {
    entities=new ArrayList<Entity>();
  }
  entities.add(entity);
  return this;
}

public Builder entity ( Entity entity ) { if ( entities == null ) { entities = new ArrayList < Entity > ( ) ; } entities . add ( entity ) ; return this ; }
adds an entity to the list of entities to be send as part of the request .
