JWT creation in Rest Controller after validating user

AuthenticationControllerCreatingJWT.java

import io.jsonwebtoken.Jwts;
import io.jsonwebtoken.SignatureAlgorithm;

@RestController
public class AuthenticationController { ...
	
@ApiOperation(value = "Validate the user login")
	@PostMapping("/api/authentication/login")
	public ResponseEntity<?> userLogin(@RequestBody User user) {
		String jwtToken = "";
		try {
			jwtToken = getToken(user.getUserId(), user.getUserPassword());
			map.clear();
			map.put("message", "user successfully logged in");
			map.put("token", jwtToken);
		} catch (Exception e) {
			String exceptionMessage = e.getMessage();
			map.clear();
			map.put("token", null);
			map.put("message", exceptionMessage);
			return new ResponseEntity<>(map, HttpStatus.UNAUTHORIZED);
		}
		return new ResponseEntity<>(map, HttpStatus.OK);
	}

	// Generate JWT token
	public String getToken(String username, String password) throws Exception {
		if (username == null || password == null) {
			throw new ServletException("username and password is required");
		}
		User user = userAuthenticationService.findByUserIdAndPassword(username, password);
		if (user == null) {
			throw new UserNotFoundException("Invalid credentials.");
		}

		String jwtToken = Jwts.builder().setSubject(username).setIssuedAt(new Date())
				.setExpiration(new Date(System.currentTimeMillis() + EXPIRATIONTIME))
				.signWith(SignatureAlgorithm.HS256, "secretkey").compact();

		return jwtToken;
	}