design.xml

<?xml version="1.0"?>
<!--
/**
 * Copyright © Magento, Inc. All rights reserved.
 * See COPYING.txt for license details.
 */
-->
<ruleset name="Magento Specific Design Rules"
         xmlns="http://pmd.sf.net/ruleset/1.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://pmd.sf.net/ruleset/1.0.0 http://pmd.sf.net/ruleset_xml_schema.xsd"
         xsi:noNamespaceSchemaLocation="http://pmd.sf.net/ruleset_xml_schema.xsd">
    <rule name="FinalImplementation"
          class="Magento\CodeMessDetector\Rule\Design\FinalImplementation"
          message= "The {0} {1} declared as final.">
        <description>
            <![CDATA[
Final keyword is prohibited in Magento as this decreases extensibility and customizability.
Final classes and method are not compatible with plugins and proxies.
            ]]>
        </description>
        <priority>1</priority>
        <properties />
        <example>
            <![CDATA[
final class Foo
{
    public function bar() {}
}
class Baz {
    final public function bad() {}
}
            ]]>
        </example>
    </rule>
</ruleset>