Below is reactjs code

  import { apiSlice } from './apiSlice.js';

const AUTH_URL = '/auth';

export const authApiSlice = apiSlice.injectEndpoints({
    endpoints: (builder) => ({
        login: builder.mutation({
            query: (credentials) => ({
                url: `${AUTH_URL}/login`,
                method: 'POST',
                body: credentials,
            }),
        }),
    }),
    overrideExisting: false,
});

export const { useLoginMutation } = authApiSlice;

const baseQuery = fetchBaseQuery({
    baseUrl: 'http://localhost:8080',
    prepareHeaders: (headers) => {
        headers.set('Content-Type', 'application/json');
        return headers;
    },
})

export const apiSlice = createApi({
    baseQuery,
    tagTypes: ['Auth'],
    endpoints: (builder) => ({})
})

import { configureStore, Tuple } from '@reduxjs/toolkit';
import authReducer from './authSlice';
import {apiSlice} from '../slices/apiSlice.js'


const store = configureStore({
    reducer: {
        auth: authReducer,
        [apiSlice.reducerPath]: apiSlice.reducer,
    },
    middleware: (getDefaultMiddleware) =>
        getDefaultMiddleware().concat(apiSlice.middleware),
    devTools: true
});

export default store;

below is the handler in which api is being called and getting response, response is good, but not able to fetch or see headers in logs or console in chrome, i can see headers in postman/insomnia

const handleLogin = async () => {
        if (!username || !password) {
            setError('Please fill in all fields');
            return;
        }
        setError(``)
        try {
            const response = await login({ username, password }).unwrap();
            console.log(response)
            const token = response.headers.get('Authorization');
            if (token) {
                localStorage.setItem('token', token);
            }
            dispatch(setCredentials(response.data));
            navigate('/dashboard');
        } catch (err) {
            console.log(err)
            {err.data && err.data['message'] ? setError('Login failed: ' + err.data['message']) : setError('Login failed: ' + err.status)}
        }
    };

Below is server’s endpoint, here i’m binding header with response and send to the client

@PostMapping("/login")
public ResponseEntity<ApiResponse> loginUser(@RequestBody User user) {
    User existingUser = userService.findByUsernameAndPassword(user.getUsername());
    if (existingUser == null) {
        return ResponseEntity.status(401).body(new ApiResponse("User not found", null));
    }
    if (passwordEncoder.matches(user.getPassword(), existingUser.getPassword())) {
        if (existingUser.isVerified()) {
            String token = jwtUtil.generateToken(existingUser.getUsername(), existingUser.getRole());
            UserDTO userDTO = userEntityToUserDTO.mapToDTO(existingUser);
            HttpHeaders headers = new HttpHeaders();
            headers.set("Authorization", "Bearer " + token);
            return ResponseEntity.ok().headers(headers).body(new ApiResponse("Login successful", userDTO));
        } else {
            return ResponseEntity.status(401).body(new ApiResponse("User not verified", null));
        }
    } else {
        return ResponseEntity.status(401).body(new ApiResponse("Invalid credentials", null));
    }
}