Revision 31d78d3d-be2d-45c7-b814-4559e1ec7e2a

I have to add bootstrap 3 or 4 to my custom theme (magento 2.2.5)
I tried this:
[How to use bootstrap in my custom theme][1]
and this
[Bootstrap in magento 2 theme][2]
but these ways don't work with magento 2.2.5

  [1]: https://devdocs.magento.com/guides/v2.3/config-guide/bootstrap/magento-bootstrap.html
  [2]: https://magento.stackexchange.com/questions/195508/how-to-use-bootstrap-in-my-custom-theme/#answer-195553

    <?xml version="1.0"?>
<!--
/**
 * Copyright © 2015 Magento. All rights reserved.
 * See COPYING.txt for license details.
 */
-->
<page xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:View/Layout/etc/page_configuration.xsd">
    <head>	
		<css src="css/bootstrap.css" />
		<css src="css/bootstrap.css.map" />
		<css src="css/bootstrap.min.css" />
		<css src="css/bootstrap.min.css.map" />
		<css src="css/bootstrap-grid.css" />
		<css src="css/bootstrap-grid.css.map" />
		<css src="css/bootstrap-grid.min.css" />
		<css src="css/bootstrap-grid.min.css.map" />
		<css src="css/bootstrap-reboot.css" />
		<css src="css/bootstrap-reboot.css.map" />
		<css src="css/bootstrap-reboot.min.css" />
		<css src="css/bootstrap-reboot.min.css.map" />
     
         
        <css src="owl.carousel/assets/owl.carousel.css" />
	
	
       
    </head>
</page>

default_head_blocks.xml

    var config = {
    paths: {
            'bootstrap':'Magento_Theme/js/bootstrap.bundle',
    } ,
    shim: {
        'bootstrap': {
            'deps': ['jquery']
        }
    }
};

Magento_Theme/requirejs-config.js

Also I added Bootstrap css flies at (vendor/my_theme/web/css)
and added Bootstrap js files at (vendor/my_theme/Magento_Theme/web/js)
I use bootstrap 4 and magento 2.2.5