Wrong "metadata" property type in the jslack.api.model.Attachment

[nikitayefanov]

Now it is String but I believe that it should be Object or some custom class because when I fetch conversation history for a conversation in files.attachments.metadata I receive an object but not a String, and because of that I'm getting a

com.google.gson.JsonSyntaxException: java.lang.IllegalStateException: Expected a string but was
BEGIN_OBJECT at line 1 column 60127 path $.messages[29].files[0].attachments[0].metadata

I'm attaching the JSON file with an example of a message I get when I try to get conversations history.