Use mockito to mock method with Object parameter

I have a method :

public class Sender{
  public Object send(Object param){
    Object x;
    .....
    return (x);
  }
}

I want to write a unit test for this method using Mockito such that the return type value is based on the class type of the paramter. So I did this:

when(sender.send(Matchers.any(A.class))).thenReturn(value1);
when(sender.send(Matchers.any(B.class))).thenReturn(value2);

but the return value irrespective of the parameter class type is always value 2. How do it get this to return value 1 for class A type argument and value 2 for class B type argument.