public static List<String> pluginClasses(TestPlugin... plugins) {
        assertAvailable();
        return Arrays.stream(plugins)
                .filter(Objects::nonNull)
                .map(TestPlugin::className)
                .distinct()
                .collect(Collectors.toList());
    }
Get all plugin classes which are included in the specified plugins
@param plugins One or more plugins which are included in the plugin path.
@return A list of plugin class names
@throws AssertionError if any plugin failed to load, or no plugins were loaded.
connect/runtime/src/test/java/org/apache/kafka/connect/runtime/isolation/TestPlugins.java