The BSON library currently has a (private) method on the Bson type that converts it into a document with keys and values mirroring the extended JSON representation of the type. This is currently used in the implementation of serde decoding/encoding, but it duplicates a lot of the logic in the extended JSON implementation. We should investigate if it's possible to either update the serde implementation so that it doesn't need this functionality or unify the logic between this method and the extended JSON implementation.