system/Entity.php
protected function hasPropertyChanged(string $key, $value = null): bool
	{
		return ! (($this->_original[$key] === null && $value === null) || $this->_original[$key] === $value);
	}
protected function hasPropertyChanged(string $key, $value = null): bool
	{
		return ! (($this->_original[$key] === null && $value === null) || $this->_original[$key] === $value);
	}
Checks a property to see if it has changed since the entity was created.

@param string $key
@param null   $value

@return boolean