@Override
        public boolean commit(boolean dryRun) throws IOException, TerseException {
            boolean changed = false;
            for (Map.Entry<Path, Map<PluginType, Set<String>>> manifestSource : manifests.entrySet()) {
                Path jarPath = manifestSource.getKey();
                Map<PluginType, Set<String>> before = initial.get(jarPath);
                Map<PluginType, Set<String>> after = manifestSource.getValue();
                if (startSync(dryRun, jarPath, before, after)) {
                    rewriteJar(dryRun, jarPath, after);
                    changed = true;
                }
            }
            return changed;
        }
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