Generic Error Response on Token Endpoint

[KaveeshaPiumini]

Purpose

This PR unifies the error_description of the the OAuth2 authentication requests with the following grant types.

• Refresh token grant
• Client credentials grant
• Password grant
• Token exchange grant
• SAML 2.0 bearer grant
• Organization switch grant

When the Client ID/Client Secret is incorrect, now the related endpoints will return the following error.

{
    "error_description": "Client credentials are invalid.",
    "error": "invalid_client"
}

Related Issue

• Requesting Generic Error Response on Token Endpoint wso2/product-is#22336

[jenkins-is-staging]

PR builder started
Link: https://github.com/wso2/product-is/actions/runs/12947480266

[codecov]

Codecov Report

Attention: Patch coverage is 33.33333% with 2 lines in your changes missing coverage. Please review.

Project coverage is 54.07%. Comparing base (72b70c8) to head (f4067e3).
Report is 26 commits behind head on master.

Files with missing lines	Patch %	Lines
...client/authentication/OAuthClientAuthnService.java	33.33%	2 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #2691      +/-   ##
============================================
- Coverage     55.94%   54.07%   -1.88%     
- Complexity     8772     8845      +73     
============================================
  Files           654      654              
  Lines         50916    54016    +3100     
  Branches       9985    11163    +1178     
============================================
+ Hits          28485    29208     +723     
- Misses        18365    20566    +2201     
- Partials       4066     4242     +176     

Flag	Coverage Δ
unit	39.50% <33.33%> (-0.09%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[jenkins-is-staging]

PR builder completed
Link: https://github.com/wso2/product-is/actions/runs/12947480266
Status: failure