问Java SecurityManager -如何确保一个方法只由另一个方法运行？

EN

public final class A{
    private transient final B sensitiveHolder; //set at Constructor
    public A(B sensitiveHolder){
        this.sensitiveHolder = sensitiveHolder;
    }
    private final byte[] getSensitiveData(){
        return sensitiveHolder.getSensitiveData();
    }
}

public final class B{
    private transient final byte[] sensitiveData;//encrypt and set at Constructor
    public final byte[] getSensitiveData(){
        //check if it is run by A#getSensitiveData(); if it is, decrypt by DEK and give plaintext.
    }
}