Description:
------------
It is possible to access the protected property of class A within the class B if
both classes have the same parent - C, that defined the property
unless the property is overriden in child class A or B

Test script:
---------------
<?php
class C
{
  protected $data;
}

class A extends C
{
}

class B extends C
{
  public function test()
  {
    $obj = new A();
    $obj->data = 'Hello world';
    
    echo $obj->data;
  }
}
?>

Expected result:
----------------
Unless the class B is not the child of the class A, an error must be risen
when trying to access the protected property of the class A within class B