HttpClient distinguishes three kinds of entities, depending on where their content originates:
streamed: The content is received from a stream, or generated on the fly. In particular, this category includes entities being received from HTTP responses. Streamed entities are generally not repeatable.
self-contained: The content is in memory or obtained by means that are independent from a connection or other entity. Self-contained entities are generally repeatable. This type of entities will be mostly used for entity enclosing HTTP requests.
wrapping: The content is obtained from another entity.