src/main/java/com/pt/testResponse/TestController.java

package com.pt.testResponse;

import org.springframework.web.bind.annotation.CrossOrigin;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
@CrossOrigin(origins = "*")
public class TestController {

    @GetMapping("/api/test")
    public String testResponse() {
        return "Hello, world!";
    }
}