v2 - inspect for mutations in serialization methods

[baywet]

in #2079 I've fixed a but where the serialization code was mutating the object.
This is an issue since if you serialize the same object multiple times, you might get different results. (or depending on the ordering v2/v3)

We should inspect all serialization methods to ensure there are no more mutations of the properties, sub-objects in the serialization code.