@Override
    protected Class<?> loadClass(String name, boolean resolve) throws ClassNotFoundException {
        String fullName = aliases.getOrDefault(name, name);
        PluginClassLoader pluginLoader = pluginClassLoader(fullName);
        if (pluginLoader != null) {
            log.trace("Retrieving loaded class '{}' from '{}'", fullName, pluginLoader);
            return pluginLoader.loadClass(fullName, resolve);
        }

        return super.loadClass(fullName, resolve);
    }
Retrieve the PluginClassLoader associated with a plugin class
@param name The fully qualified class name of the plugin
@return the PluginClassLoader that should be used to load this, or null if the plugin is not isolated.
connect/runtime/src/main/java/org/apache/kafka/connect/runtime/isolation/DelegatingClassLoader.java