Enhance user registry api

[karel-harjono]

• I have considered the risk of behavior change or other zero migration impact (https://github.com/OpenLiberty/open-liberty/wiki/Behavior-Changes).
• If this PR fixes an Issue, the description includes "Fixes #FILLMEIN" or "Resolves #FILLMEIN" (verify release bug label if applicable: https://github.com/OpenLiberty/open-liberty/wiki/Open-Liberty-Conventions).
• If this PR resolves an external Known Issue (including APARS), the description includes "Fixes #FILLMEIN" or "Resolves #FILLMEIN".

[karel-harjono]

Cancelled

!build
(view Open Liberty Personal Build - ❌ completed with errors/failures.)
fat.buckets.to.run=com.ibm.ws.security.registry.basic_fat

Note: Target locations of links might be accessible only to IBM employees.

[LibbyBot]

Code analysis and actions

DO NOT DELETE THIS COMMENT.

• 6 product code files were changed.
• Please describe in a separate comment how you tested your changes.

[karel-harjono]

!build
(view Open Liberty Personal Build - ❌ completed with errors/failures.)
fat.buckets.to.run=com.ibm.ws.security.registry.basic_fat

Note: Target locations of links might be accessible only to IBM employees.

[LibbyBot]

Code analysis and actions

DO NOT DELETE THIS COMMENT.

• 6 product code files were changed.
• Please describe in a separate comment how you tested your changes.