A problem with getting response from Spring Boot after a fetch request - reactjs

Question

I have a very annoying issue. I have this Javascript code inside a React component:
let entityJson = JSON.stringify(entityObject);
fetch("http://localhost:8080/add", {
method: "POST",
mode: "no-cors",
headers: { "Content-Type" : "application/json charset=UTF-8"},
body: entityJson
}).then(data => console.log(data));
This is sending a request to the follow function in an Spring Boot Rest controller:
#PostMapping(produces = "application/json")
public AddEntityResponse newEntity(#RequestBody String person, HttpServletResponse response) {
AddEntityResponse respons = new AddEntityResponse(0,0);
Gson jsonReader = new Gson();
try{
Person newPerson = jsonReader.fromJson(person, Person.class);
personStore.addPerson(newPerson);
respons.setStatus(1);
respons.setId(newPerson.getId());
}catch(Exception e){
System.out.println(e.toString());
}
return respons;
}
But regardless of what I add, this is the request I am getting an empty response, so I guess the issue is in the Java code. I am learning this stuff now, started today so sorry if this seem a bit stupd.