def [](key)
      entity = new_entity
      key_property = entity.get_property(entity.primary_key)
      key_property.value = key

      result = service.execute("#{name}(#{key_property.url_value})")
      entities = service.find_entities(result)
      single_entity_from_xml(entities)
    end
def [](key)
      entity = new_entity
      key_property = entity.get_property(entity.primary_key)
      key_property.value = key

      result = service.execute("#{name}(#{key_property.url_value})")
      entities = service.find_entities(result)
      single_entity_from_xml(entities)
    end
Find the Entity with the supplied key value.
 @param key [to_s] primary key to lookup
 @return [OData::Entity,nil]