Function called from another package cannot access to parameters

Here is my problem :

I'm having two classes: class A contains some @Value("${param.username}") and @Value("${param.password}"), I have a function using those 2 params, and I a use @GetMapping(path = "/functionA") to run the functionA (this function is a Post request to a server to authentificate)

Username and password are on application-contextual-values.properties

When I run on browser localhost:8080/app/functionA => it works !

I have another class B, on another package B, I want to call the first class A and use the fuctionA to authentificate. => I'm having an error : Username must not be null

It means that I cannot get username and password that are stored in application-contextual-values file.

Here is my code of class A :

public class A {
    @Value("${param.username}")
    private String username;
    @Value("${param.password}")
    private String password;
    @GetMapping(path = "functionA")
    public AuthentificationModel getClient() {
        HttpHeaders headers = new HttpHeaders();
        headers.setBasicAuth(this.username, this.password);
        String jwt = getJWT(); <======  this function is also in this class A
        
        ...
     
        I'm doing a construction of params, to send on POST 
        return token;
     }

The AuthentificationModel is just what is sent back after the POST request (access_token, client_id, token_type)

My class B is :

import fr.ag2rlamondiale.ytb.rest.A; <==== class A
public class B {
   private static Map<String, String> getRequestHeader() {
       Map<String, String> requestHeaders = new HashMap<>();
       try{
         final A objA = new A(); <===== instance of my class A here
           String token = objA.getClient().getAccessToken(); <==== getClient() is the funct that returns token on class A
           requestHeaders.put("Authorization", "Bearer ", + token); 
             
           ... many other put for header
         } catch (CommonException e) {
		e.printStackTrace();
	}
	return requestHeaders;
}

My application-contextual-values.properties :

param.username="kljkjsdf555sdf"
param.password="xxx222xxx"

Is it because I'll need to add constructor on class A with params username and password ? what is the proper way to make it work in my context ?

Edit :

In class A I added : @Controller

In class B : I added @Authowired A objA and no new A();

But now, having a new error : Cannot make a static reference to the non-static field objA

Meaning that elements on class A are non-static and I'm using objA as a static object ?

Use Dependency injection and @Autowired Your A instance in B and don't create new Instance of A in your B class.

Spring can process only the objects that it manages (read creates), including resolution / injection of data annotated with @Value of course.

When you create the instance of class A by yourself from class B:

final A objA = new A();

Spring has no idea that this class must be processed, in fact it doesn't even know that this class exists, hence the "value" in not injected/set.

In general to solve this, you need to refactor your code.
Its not clear why do you create the class of Controller (I assume that A is a controller because it's method getClient is annotated with @GetMapping which makes sense only in controllers).

However, you don't have to create an instance of A, but rather inject it and make sure that both A and B are managed by Spring

Since you are creating instance of A using A objA = new A() in class B, spring does not inject any value in class A as it is new object. To use property injection in class A, you need to use dependency injection and use bean of A already instantiated using spring application context.

I assume Class A is annotated with @Controller.

@Controller
public class A {

and use autowiring in class B like below to inject instance of A

public class B {
   @Autowired
   A objA;
   private static Map<String, String> getRequestHeader() {
       Map<String, String> requestHeaders = new HashMap<>();
       try{
         //final A objA = new A(); <===== instance of my class A here
           String token = objA.getClient().getAccessToken(); <==== getClient() is the funct that returns token on class A