Issue #3123070: Fix 'PSR2.Classes.PropertyDeclaration.Underscore' coding standard

core/phpcs.xml.dist

@@ -226,6 +226,8 @@
 
   <!-- PSR-2 sniffs -->
   <rule ref="PSR2.Classes.PropertyDeclaration">
+     <!-- Silence method name underscore warning which is covered already in
+       Drupal.Classes.PropertyDeclaration. -->
     <exclude name="PSR2.Classes.PropertyDeclaration.Underscore"/>
   </rule>
   <rule ref="PSR2.Namespaces.NamespaceDeclaration"/>