Rename Association#object_id to #xero_object_id to avoid shadowing Kernel#object_id

[peterc]

Summary

• Renames object_id to xero_object_id on the XeroRuby::Files::Association model to avoid shadowing Kernel#object_id, which is a core Ruby method that should never be overridden.
• The JSON serialization key (ObjectId) is unchanged, so wire compatibility is preserved.
• API method signatures in FilesApi are unaffected (they use object_id as a local parameter name, not a model accessor).

Why this matters

Defining attr_accessor :object_id on any Ruby object overrides Kernel#object_id, which Ruby uses internally for object identity. This causes a warning (redefining 'object_id' may cause serious problems) and can lead to subtle bugs in equality checks, hash lookups, and debugging tools.

[peterc]

Fixes #327 and #348 BTW

[rept]

Hope this can get merged soon.

[SteveRawlinson]

Yes, let's get this merged in. Thanks Peter.

[octave]

Any chance to merge it soon?

[formigarafa]

I have a feeling this change won't be accepted. It looks like most (if not all of) this code is generated from their OpenAPI Spec (https://github.com/XeroAPI/Xero-OpenAPI).
And I think this object_id is a overlook from part of the OpenAPITools team which I believe did not set object_id as a reserved word for Ruby.
The list of recognised reserved words for this client is here: https://openapi-generator.tech/docs/generators/ruby#reserved-words
Unless there is a way to add items to that list via config I guess this will be delayed until, at least, the OpenAPITools is fixed.

I've found a similar PR adding object_id as reserved word for Crystal: OpenAPITools/openapi-generator#22577