fix: handle nullable discriminator fields in JWKS models

[BinoyOza-okta]

Fix: Handle Nullable Discriminator Fields in JWKS Models

Summary

This PR fixes JWKS (JSON Web Key) deserialization failures when the Okta API returns null values for fields that were incorrectly marked as required in the OpenAPI specification. The fix is template-based to ensure it persists through SDK regeneration.

Problem

Customers reported that list_applications() would fail with:

ValueError: Failed to lookup data type from the field `use` in the input.

This occurred when JWKS keys in application credentials contained null values for fields like use, kid, or kty, which are common in real Okta API responses.

Solution

Template Changes (Permanent)

1. openapi/templates/model_generic.mustache

   • Added null discriminator handling in from_dict() method
   • Returns base class instance when discriminator is null instead of raising ValueError

2. openapi/api.yaml

   • Marked fields as nullable: true: created, lastUpdated, kty, alg, use, e, n
   • Removed these fields from required lists

Other Changes

• Updated documentation with [nullable] tags

Files Changed

Templates (Permanent):

• openapi/templates/model_generic.mustache
• openapi/api.yaml

Generated Models (Auto-regenerated):

• 30+ model files in okta/models/

Documentation:

• docs/OAuth2ClientJsonSigningKeyResponse.md
• docs/OAuth2ClientJsonWebKeyRsaResponse.md

Backward Compatibility

✅ 100% backward compatible

• Existing code with non-null values continues to work
• New code can now handle null values gracefully
• No breaking changes

Usage Example

Before (Broken):

apps = await client.list_applications()
# ValueError: Failed to lookup data type from the field `use`

After (Fixed):

apps = await client.list_applications()
# Works correctly even when JWKS keys have null fields

[aniket-okta]

Checked out branch 1127600, ran 16/16 tests (9 unit + 7 integration) against the preview org. Three critical bugs confirmed — each with a failing test proving it. Fixes applied locally, all tests pass.

[aniket-okta]

Review pass 2 — branch re-tested at 0733553e after the two new commits.

Ran 29/29 unit tests (RSA, EC, discriminator, round-trip) + live-org integration against all 18 apps. All RSA e/n fields now correctly populated; EC x/y/crv round-trip clean. Two items remain open — see inline comments.

[aniket-okta]

✅ Approved — verified at 35a3da45.

29/29 unit tests pass, live-org integration clean across all 18 apps. RSA e/n and EC x/y/crv correctly serialized. kty correctly back to required per API spec.

One follow-up: please commit the test files (test_jwks_models_comprehensive.py, test_model_contradictions.py) into tests/ so they run in CI.