Deserialize JSON merge patch as JsonValue

[patveck]

Fix for #27

[cowtowncoder]

Sounds good, as per discussion. Aside from CLA (thanks for the email explaining the situation), would it be possible to add same change for jakarta-jsonp module? Due to awkward relationship between "old" JAXP and new "Jakarta", there are 2 modules which are almost identical, save for dependency to one API version or the other.

Another question is whether JsonPatchDeserializer might need changes too.

[patveck]

Thanks! I've applied the same changes for JSON Merge Patch in the jakarta-jsonp module.

Indeed, also JsonPatchDeserializer throws several different types of exceptions when the input is not an array, including an NPE. However, the situation is somewhat different: the relevant RFC explicitly states that a JSON Patch is an array of objects (Section 3, first sentence). Section 5 of the same says that evaluation of the patch should terminate if the a normative requirement is violated (emphasis mine). Indeed, the Glassfish implementation of JsonPatch#apply checks whether all elements are objects.

Consequently, I think it is sufficient for Jackson to check whether the input is an array and there's no need to iterate over its elements (that's the job of JsonPatch#apply). In case the input is not an array, we should throw an exception; I think InvalidFormatException is the appropriate one.

I've updated the PR for JsonPatch, but only in the jsr-353 module for now (I'll update the jakarta-jsonp once jsr-353 is stable).