Moved attribute value resolution to Attribute class

[HassanAkbar]

fixes #46

[Copilot]

Pull request overview

This PR implements issue #46 by consolidating attribute default resolution and value-map handling into Lutaml::Model::Attribute, and removing the now-redundant DefaultValueResolver service. It also refactors custom-method serialization call sites to use small helper methods and adds regression specs to lock in edge-case behavior.

Changes:

• Move default resolution behavior (default presence checks, proc execution in instance context, casting usage at call sites) off Services::DefaultValueResolver and into Attribute methods.
• Move/centralize value-map application into Attribute#apply_value_map, updating transform/serialization codepaths to delegate to it.
• Add regression tests around nil/omitted handling and value-map behavior; remove tests and code for DefaultValueResolver.

Reviewed changes

Copilot reviewed 20 out of 20 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
spec/lutaml/model/transform_apply_value_map_spec.rb	Adds regression coverage for Transform#apply_value_map when attr is nil (custom-method-only rules).
spec/lutaml/model/services/default_value_resolver_spec.rb	Removes specs for the deleted DefaultValueResolver service.
spec/lutaml/model/rule_value_extractor_spec.rb	Updates tests to use real Attribute + default register now that defaults resolve via Attribute.
spec/lutaml/model/attribute_spec.rb	Adds/updates specs to validate default resolution, caching behavior, and validate_value! threading instance context.
spec/lutaml/model/attribute_apply_value_map_spec.rb	Adds focused coverage for Attribute#apply_value_map across nil/empty/omitted and boolean map formats.
lib/lutaml/xml/document.rb	Extracts apply_custom_to helper for XML serialization custom-method dispatch.
lib/lutaml/xml/adapter/plan_based_builder.rb	Uses apply_custom_to helper instead of repeating public_send dispatch logic.
lib/lutaml/xml/adapter/base_adapter.rb	Uses apply_custom_to helper for content mapping custom-method serialization.
lib/lutaml/model/validation.rb	Removes DefaultValueResolver usage; validates using instance_object: threading to Attribute#validate_value!.
lib/lutaml/model/transform.rb	Delegates value-map application to Attribute#apply_value_map, with a safe fallback for attr-less rules.
lib/lutaml/model/services/rule_value_extractor.rb	Removes DefaultValueResolver usage; pulls defaults via Attribute#default_value.
lib/lutaml/model/services/default_value_resolver.rb	Deletes the DefaultValueResolver service implementation.
lib/lutaml/model/services.rb	Removes autoload entry for the deleted service.
lib/lutaml/model/serialize/value_mapping.rb	Delegates value-map application to Attribute#apply_value_map.
lib/lutaml/model/serialize.rb	Updates default determination to resolve raw default once, then cast, avoiding prior double-proc execution.
lib/lutaml/model/schema/generator/property.rb	Switches schema default extraction to Attribute#default_value + cast instead of the removed service.
lib/lutaml/model/mapping/mapping_rule.rb	Removes unused serialize_attribute helper (custom serialization already handled elsewhere).
lib/lutaml/model/attribute.rb	Adds Attribute#apply_value_map and updates validate_value! to resolve defaults via attribute methods.
lib/lutaml/key_value/transformation.rb	Refactors serialize-side custom-method invocation into an apply_custom_to helper.
lib/lutaml/key_value/transform.rb	Refactors serialize-side custom-method invocation into an apply_custom_to helper and simplifies custom-method deserialization dispatch.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.