Return client error responses as structured JSON in the User Sharing API

[BimsaraBodaragama]

This PR updates the User Sharing API to return client error responses in a structured JSON format instead of plain text, ensuring consistency with other API responses. Additionally, it refactors the error handling logic by moving it from UsersApiServiceImpl to UsersApiServiceCore, improving maintainability and reducing redundant code.

Purpose

• Standardize error responses across the API.
• Improve error debugging and traceability by including traceId, errorCode, message, and description in the response.
• Enhance code maintainability by centralizing error-handling logic.

Goals

• Ensure all client error responses follow a structured JSON format.
• Enhance the developer experience by making error responses more informative.
• Reduce code duplication and improve maintainability by restructuring error handling.

Approach

• Replaced plain text error responses with a structured JSON format.
• Introduced the Error model to encapsulate error details.
• Introduced the buildErrorResponse method to generate JSON responses containing:
  • traceId: Unique identifier for debugging.
  • errorCode: Specific error code for identification.
  • message: Short summary of the error.
  • description: Detailed explanation of the error.
• Moved error handling logic from UsersApiServiceImpl to UsersApiServiceCore to improve modularity.
• Refactored UsersApiServiceCore by introducing private methods to eliminate redundant code and enhance readability.

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Related Issue

product-is issue: Client error responses of user sharing API should be returned as JSON responses #22596

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Link: https://github.com/wso2/product-is/actions/runs/13048121047

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Approving the pull request based on the successful pr build https://github.com/wso2/product-is/actions/runs/13048121047

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PR builder started
Link: https://github.com/wso2/product-is/actions/runs/13052855765

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PR builder completed
Link: https://github.com/wso2/product-is/actions/runs/13052855765
Status: success

[jenkins-is-staging]

Approving the pull request based on the successful pr build https://github.com/wso2/product-is/actions/runs/13052855765