2.0.0
Raw attachment content data must be passed in order to make it possible for serializer implementiations to populate the $content attribute of Attachment objects during deserialization.
In order to achieve this an optional $attachments argument has been added to the StatementResultSerializerInterface::deserializeStatementResult(), and the deserializeStatement() and deserializeStatements() methods of the StatementSerializerInterface.
When being passed, this argument must be an array mapping SHA-2 hashes to an array which in turn maps the type and content keys to the attachment's content type and raw content data respectively.