Create the classes:

package p1;
public class B extends A {
  protected long k(){
    return 2;
  }
  public long test(){
    return m();
  }
}

package p1;
public class A {
  private long k(){
    return 1;
  }
  public long m(){
    return this.k();
  }
}

apply the push down method refactoring to m 

package p1;
public class B extends A {
  protected long k(){
    return 2;
  }
  public long test(){
    return m();
  }
    public long m() {
        return this.k();
    }
}

package p1;
public class A {
  protected long k(){
    return 1;
  }
}

The transformation changes behavior. After the transformation the test method returns 2 instead of 1