core/play/src/main/java/play/http/HttpEntity.java
public CompletionStage<ByteString> consumeData(Materializer mat) {
    return dataStream().runFold(ByteString.empty(), ByteString::concat, mat);
  }
public CompletionStage<ByteString> consumeData(Materializer mat) {
    return dataStream().runFold(ByteString.empty(), ByteString::concat, mat);
  }
Consumes the data.

<p>This method should be used carefully, since if the source represents an ephemeral stream,
then the entity may not be usable after this method is invoked.

@param mat the application's materializer.
@return a CompletionStage holding the data