feat: added get userdata from jwt helper

[Julius257]

UserInformationJWT - Helper Class

The backend provides a convenient helper class UserInformationJWT to extract user information from JWT tokens, similar to the frontend's useUser hook.

Example

@RestController
public class MyController {
  @GetMapping("/my-endpoint")
  public ResponseEntity<?> myEndpoint() {
    // Get user information
    String userId = UserInformationJWT.getUserId();
    String email = UserInformationJWT.getEmail();
    String fullName = UserInformationJWT.getFullName();
    
    // Check roles
    if (UserInformationJWT.hasRole("lecturer")) {
      // Lecturer logic
    }
    
    return ResponseEntity.ok("Hello " + fullName);
  }
}

Available Methods

• getUserId() - Get user ID (subject)
• getUsername() - Get username (preferred_username)
• getEmail() - Get email address
• getFirstName() - Get first name
• getLastName() - Get last name
• getRoles() - Get all roles (from groups, realm_access, resource_access)
• hasRole(String role) - Check if user has specific role (case-insensitive)
• getClaim(String name) - Get custom JWT claim
• isAuthenticated() - Check if user is authenticated

[Copilot]

Pull Request Overview

Adds a backend helper class to extract user information from JWTs and a comprehensive test suite validating its behavior.

• Introduces UserInformationJWT with static accessors for common claims, roles aggregation, and authentication checks
• Adds unit tests that construct a representative Jwt and verify claim getters, role aggregation, case-insensitive role checks, and unauthenticated scenarios

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

File	Description
src/main/java/com/ase/userservice/security/UserInformationJWT.java	New helper class implementing claim getters, role aggregation, and auth checks
src/test/java/com/ase/userservice/security/UserInformationJWTTest.java	New tests covering claim access, roles, case-insensitive checks, and unauthenticated cases

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