What is binary attachment map?

I am trying to fetch something from a really old application which still uses solace but the problem I am facing is that the inbound message has 2 things a User Property Map and a Binary Attachment Map (which has a key “Object” where my data of interest resides)

I tried to use the get_payload_as_dictionary but the raw bianry message that I get is corrupted

but where has when the inbound message is printed as it it is printed the hex form the binary message correctly

the Legacy application was written in Java and I am suing the python library to consume some messages from the topic. I don’t see any method in the inbound message for reading the binary attachment map why ??