Why do the following code prints the stack trace and why is a.toString() in the return statement not giving an error or exception?

Following is the complete code -

import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Annotation;
import java.lang.reflect.*;

class A2<T> {
    T ob;
    A2(T ob) {
        this.ob = ob;
    }
    @Annos(str="T example")
    T retob() {
        return ob;
    }
    @Override
    public String toString() {
        Annotation a = null;
        try {
            Class<?> c = this.getClass();
            Method m = c.getMethod("retob");
            a = m.getAnnotation(Annos.class);
        }catch(NoSuchMethodException NSMe) {
            NSMe.printStackTrace();
        }
        return a==null?"EMPTY":a.toString();
    }
    public static void main(String args[]) {
        System.out.println(new A2<Integer>(2).toString());
    }
}

@Retention(RetentionPolicy.RUNTIME)
@interface Annos {
    String str();
}

If I have override the toString() method then how can a.toString() in the return statement as well as in the main method work?

Here is the output -

java.lang.NoSuchMethodException: A2.retob()
        at java.base/java.lang.Class.getMethod(Class.java:2227)
        at A2.toString(A2.java:20)
        at A2.main(A2.java:28)
EMPTY

Why is it not able to get the method retob?