Fix PHPStorm findings

[franmomu]

This doesn't fix any PHPStan issue, but some PHPStorm findings.

The PHPDoc code that has been removed is because it didn't match the method signature and once that has been fixed, php-cs-fixer removes it.

I'll add some a couple of comments in the code about the PHPDoc changes.

[franmomu]

Based on

Elastica/src/Bulk/Action.php

Lines 107 to 125 in 1e74607

	/**
	* @param array|string $source
	*
	* @return $this
	*/
	public function setSource($source): self
	{
	$this->_source = $source;
	return $this;
	}
	/**
	* @return array|string
	*/
	public function getSource()
	{
	return $this->_source;
	}