Add a config to autofill the username with subject attribute while jit provisioning

[DilshanSenarath]

Purpose

This pr will introduce the changes require to configure the auto populating username with subject attribute.

Since the auto-population of the username field with the subject attribute may already be in use by other customers, we plan to introduce a new configuration to maintain backward compatibility while providing the requested change.

We’ll add a boolean server level configuration option called AutofillUsernameFieldWithSubjectAttribute within the JITProvisioning configuration section. Before appending the username to the registration UI redirection URL, we will first verify if the prompt for username, password, and consent provisioning is enabled. If enabled, we will then check if this new configuration is set to true and, if so, add the username parameter to the registration UI redirection URL.

[authentication.jit_provisioning]
autofill_username_field_with_subject_attribute = false

Related Issue

• Username field is auto poppulated with the subject claim from Fed Auth during JIT with consented username and password flow product-is#21578

[codecov]

Codecov Report

Attention: Patch coverage is 80.00000% with 1 line in your changes missing coverage. Please review.

Project coverage is 45.75%. Comparing base (b492a3d) to head (eda1110).
Report is 25 commits behind head on master.

Files with missing lines	Patch %	Lines
...impl/JITProvisioningPostAuthenticationHandler.java	66.66%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #6225      +/-   ##
============================================
+ Coverage     45.66%   45.75%   +0.08%     
- Complexity    14040    14265     +225     
============================================
  Files          1632     1636       +4     
  Lines        100532   102406    +1874     
  Branches      17421    16824     -597     
============================================
+ Hits          45911    46852     +941     
- Misses        47931    48791     +860     
- Partials       6690     6763      +73     

Flag	Coverage Δ
unit	28.33% <80.00%> (+0.03%)	⬆️

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[jenkins-is-staging]

PR builder started
Link: https://github.com/wso2/product-is/actions/runs/12412180506

[jenkins-is-staging]

PR builder completed
Link: https://github.com/wso2/product-is/actions/runs/12412180506
Status: failure

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[jenkins-is-staging]

PR builder started
Link: https://github.com/wso2/product-is/actions/runs/12412684012

[jenkins-is-staging]

PR builder completed
Link: https://github.com/wso2/product-is/actions/runs/12412684012
Status: failure

[jenkins-is-staging]

PR builder started
Link: https://github.com/wso2/product-is/actions/runs/12415024786

[jenkins-is-staging]

PR builder completed
Link: https://github.com/wso2/product-is/actions/runs/12415024786
Status: success

[jenkins-is-staging]

Approving the pull request based on the successful pr build https://github.com/wso2/product-is/actions/runs/12415024786

[piraveena]

DO we need this config for master?

[DilshanSenarath]

DO we need this config for master?

Yes, this feature allows auto-populating the subject attribute value from the federated IDP during username and password provisioning. Therefore, we need to retain the existing behavior. However, a specific customer, who does not have a unique attribute other than the resource ID in their federated IDP, requested the ability to disable the auto-filling capability. As this could be a general requirement, the PR has been created to address it.