UnauthorizedHandler.java

public class UnauthorizedHandler implements AuthenticationEntryPoint {

    private ObjectMapper mapper = new ObjectMapper();

    public void commence(HttpServletRequest request,
                         HttpServletResponse response,
                         AuthenticationException authenticationException)
            throws IOException, ServletException {

        String authorizationToken = request.getHeader(HttpHeaders.AUTHORIZATION);
        String message = (authorizationToken != null) ? "Invalid token" : authenticationException.getMessage();

        ErrorResponse errorResponse = ErrorResponse.builder()
                .errorCode(HttpServletResponse.SC_UNAUTHORIZED)
                .errorMessage(message).build();
        response.setContentType("application/json");
        response.setStatus(HttpServletResponse.SC_UNAUTHORIZED);
        response.getOutputStream().println(mapper.writeValueAsString(errorResponse));

    }

}