correct the name of the editors-xtd group plugins class

editors-xtd group plugins class name must have a (plgButton<PluginName>) structure, but JCB creates the names of these classes with (plg<PluginGroup><PluginName>) structure, which makes this type of plugins not work

admin/helpers/componentbuilder.php

@@ -6587,8 +6587,22 @@ abstract class ComponentbuilderHelper
 			return array_values($fieldIds);
 		}
 		return false;
-	}
-
+	}
+
+        /**
+         * create plugin class name
+         */
+        public static function createPluginClassName($group, $code_name)
+        {
+            // editors-xtd group plugins must have a class with plgButton<PluginName> structure
+            if ($group == 'editors-xtd')
+                $group= 'Button';
+
+            return 'Plg' . ucfirst($group) . ucfirst(
+                    $code_name
+                );
+        }
+  
 	/**
 	 * get a plugin fields IDs
 	 */