[Bug] Calling a value is not thread safe (return another value)

I noticed that when calling values ​​from different threads, it can returns values ​​from other methods. The wrong method is invoked somehow. Bug reproduced on version 1.0.11 I tried 1.0.8 - 1.0.10 and all ok.

src/test/resources/config.properties

firstName=Pasha
lastName=Bairov

---

import org.aeonbits.owner.Config;

@Config.Sources({"file:src/test/resources/config.properties"})
public interface MyConfig extends Config {

    @Key("firstName")
    String firstName();

    @Key("lastName")
    String lastName();
}

---

public static void main(String[] args) {
        MyConfig cfg = ConfigFactory.create(MyConfig.class);


        new Thread(() -> {
            for (int i = 0; i < 1000; i++) {
                String name = cfg.firstName();

                if (!name.equals("Pasha")) {
                    System.out.println("name " + name);
                }
            }
        }).start();

        new Thread(() -> {
            for (int i = 0; i < 1000; i++) {
                cfg.lastName();
            }
        }).start();
    }

---

I executed it 1000 times and here it stdout:

name Bairov
name Bairov
name Bairov
name Bairov
name Bairov

---

I can provide any necessary information for debugging.

[lviggiano]

@Amerousful Glad it helped. Thank you for your valuable time in helping.

[lviggiano]

thank you for the unit test, really appreciated you took the time to produce a test case to reproduce the issue. I wrote a unit test inspired to your code. So this issue hopefully will not show up again.