[Endpoints BDD 2/5] Codegen baseline BDD Resolver

[alextwoods]

[Endpoints BDD 2/5] Codegen baseline BDD Resolver

This PR is 2/5 for the Endpoints BDD. This is part of a Github PR Stack - to see all of the PRs in the stack, see the "2/5" at the top of the PR.

Note: This PR merges to the feature/master/endpoints-bdd feature branch and NOT to master.

Modifications

Adds code generation visitors that transform a BDD (Binary Decision Diagram) endpoint model into a Java endpoint provider. When an endpoint-bdd-1.json is present in a service's codegen-resources, the codegen emits a BDD-based resolver instead of the tree-based rules resolver. Each BDD node becomes a method that evaluates its condition and branches to child nodes or results, returning Endpoint directly. The generated resolver is validated end-to-end against 32 Connect endpoint test cases in codegen-generated-classes-test.

Changes by area:

• bdd/BddEndpointProviderSpec — Main spec: builds the evaluator inner class with per-call allocation, emits nodeP<i> methods for each BDD node, cond<i> for complex conditions, and result<i> for endpoint/error leaves. Gates on BDD model presence (no customization flag required).
• bdd/BddResultCodeGeneratorVisitor — Walks the result RuleModel expressions to emit endpoint construction (URL, headers, auth scheme attributes) or error throws.
• bdd/ConditionFnCodeGeneratorVisitor — Emits condition evaluation code: function calls (awsPartition, substring, isValidHostLabel, etc.), getAttr member access, and assigns to evaluator registers.
• bdd/AssignTypeInferringVisitor — Infers types for BDD register variables from condition/result expressions so the evaluator fields can be declared with concrete types.
• bdd/RegistryInfo — Metadata per BDD register: Java field name, type, source expression, nullability, and whether it maps to an endpoint parameter.
• EndpointProviderTasks — Wiring: selects BddEndpointProviderSpec when BDD model is present, compiled rules otherwise.
• ClientTestModels + test fixtures — Adds queryServiceModelsWithBddEndpoints (S3 BDD) and queryServiceModelsWithSimpleBddEndpoints (simple regional service-like BDD) with corresponding JSON fixtures.
• BddEndpointProviderSpecTest — Golden-file fixture test against the small BDD, plus assertion tests for dynamic auth scheme codegen and the fail-fast on missing S3Express customization.
• test/codegen-generated-classes-test/bddendpoints — New test service with Connect's BDD + endpoint tests; auto-generated provider test validates all 32 endpoint test cases pass at runtime.

Testing

• Codegen unit tests that use golden cases

• TokenizerTest — 9 cases covering template expression tokenization including hyphen and negative-index edge cases

• BddEndpointsEndpointProviderTests (codegen-generated-classes-test, auto-generated)

  • Runs all 32 Connect endpoint test cases against the BDD-generated resolver at runtime (regions, FIPS, DualStack, custom endpoint, error cases)

Screenshots (if appropriate)

License

• I confirm that this pull request can be released under the Apache 2 license