CKEditor 4 removes &nbsp; from <p> and <div> tags that have no text

Question

How to disable &nbsp automatic removal from p and div tags that have no text? Below is an example:

<p>&nbsp;</p>   =>   <p></p>

<div>&nbsp;</div>   =>   <div></div>

If the tag has text, this does not happen:

<p>text&nbsp;</p>   =>   <p>text&nbsp;</p>

<div>text&nbsp;</div>   =>   <div>text&nbsp;</div>

This situation does not occur with the <span> tag:

<span>&nbsp;</span>   =>   <span>&nbsp;</span>