Make serial descriptor equality (and hashcode) include the declared (use side) element names, rather than only the serial names of the element types.

[pdvrieze]

The xml parser uses the serial descriptor as part of the lookup key for extended type information. However, this does not work correctly if two serial descriptors have the same name and member types, even if the element names are different. This pull request includes the declared element names as part of the hash key and equals checking (I know that multiple types with the same @SerialName is not supposed to work, but with this change it at least breaks less.

The underlying bug is pdvrieze/xmlutil#254.

[sandwwraith]

I do not think we can change equals contract at this point, since it is part of a stable API and widely used now. Besides, the whole idea of comparing descriptors by something else except serialName is tied to generic classes — so Foo<String> can be distinguished from Foo<Int>, since their serialized form would be different. If the classes in question are not two generic flavors of one class but two different classes, they have to have different serial names.

For your issue, I can recommend either prohibit duplicated serial names, or make a serial descriptor wrapper to store in your cache — the wrapper would compare both serial descriptors and element names.