Chain::addElement

public function addElement(ChainElement $element)
{
	if (empty($this->chain) && !($element->getValue() instanceof Entity))
	{
		throw new SystemException('The first element of chain should be Entity only.');
	}

	$this->chain[] = $element;
	$this->definition = null;
	$this->definitionParts = null;
	$this->alias = null;

	$this->last_element = $element;
	$this->size++;
}