Discards the entities data bytes by running the dataBytes Source contained by the entity of this HTTP message.

Note: It is crucial that entities are either discarded, or consumed by running the underlying akka.stream.javadsl.Source as otherwise the lack of consuming of the data will trigger back-pressure to the underlying TCP connection (as designed), however possibly leading to an idle-timeout that will close the connection, instead of just having ignored the data.

Warning: It is not allowed to discard and/or consume the entity.dataBytes more than once as the stream is directly attached to the "live" incoming data source from the underlying TCP connection. Allowing it to be consumable twice would require buffering the incoming data, thus defeating the purpose of its streaming nature. If the dataBytes source is materialized a second time, it will fail with an "stream can cannot be materialized more than once" exception.

When called on Strict entities or sources whose values can be buffered in memory, the above warnings can be ignored. Repeated materialization is not necessary in this case, avoiding the mentioned exceptions due to the data being held in memory.

In future versions, more automatic ways to warn or resolve these situations may be introduced, see issue #18716.

Discards the entities data bytes by running the dataBytes Source contained by the entity of this HTTP message.

Note: It is crucial that entities are either discarded, or consumed by running the underlying akka.stream.javadsl.Source as otherwise the lack of consuming of the data will trigger back-pressure to the underlying TCP connection (as designed), however possibly leading to an idle-timeout that will close the connection, instead of just having ignored the data.

Warning: It is not allowed to discard and/or consume the entity.dataBytes more than once as the stream is directly attached to the "live" incoming data source from the underlying TCP connection. Allowing it to be consumable twice would require buffering the incoming data, thus defeating the purpose of its streaming nature. If the dataBytes source is materialized a second time, it will fail with an "stream can cannot be materialized more than once" exception.

When called on Strict entities or sources whose values can be buffered in memory, the above warnings can be ignored. Repeated materialization is not necessary in this case, avoiding the mentioned exceptions due to the data being held in memory.

In future versions, more automatic ways to warn or resolve these situations may be introduced, see issue #18716.

Try to find the first header of the given class and return Optional.of(header), otherwise this method returns an empty Optional.