@Override
        public void addManifest(PluginType type, String pluginClass) {
            // Add plugins to the managed manifest
            manifests.get(location().resolve(MANAGED_PATH)).get(type).add(pluginClass);
        }
A multi-jar workspace is similar to the classpath workspace because it has multiple jars.
However, the multi-jar workspace is writable, and injects a managed jar where it writes added manifests.
tools/src/main/java/org/apache/kafka/tools/ManifestWorkspace.java