public function testSetLocalPartCannotSetToExisting()
 {
     $this->assertFalse($this->address->setLocalPart('test2'));
     $this->assertEquals('test', $this->address->getLocalPart());
 }
 private function addInstance(AddressImpl $instance)
 {
     $this->addressList[$instance->getLocalPart()] = $instance;
     $instance->attachObserver($this);
 }