@RestController
public class ControllerA {

@RequestMapping(value = "/methodA", consumes = MediaType.APPLICATION_JSON_UTF8_VALUE)
public ResponseEntity<String> methodA(@RequestBody String something) {
    // some process
    return null;
}

@RestController
public class ControllerB {

@RequestMapping(value = "/methodB", consumes = org.springframework.http.MediaType.APPLICATION_JSON_VALUE)
public ResponseEntity<String> methodA(@RequestBody String something) {
    // some process
    return null;
}

@RestController
public class ControllerC {

public ResponseEntity<String> methodC(@RequestBody String someReq) {
    if (checkPam(someReq)) {
        **// I want to call the ControllerA in serverA.**
    }else {
        **// I want to call the ControllerB in serverB.**
    }
    return null;
}