@Override
        public void addManifest(PluginType type, String pluginClass) {
            throw new UnsupportedOperationException("Cannot change the contents of the classpath");
        }
A classpath workspace is backed by multiple jars, and is not writable.
The in-memory format is a map from jar path to the manifests contained in that jar.
The control flow of the caller should not perform writes, so these exceptions indicate a bug in the program.
tools/src/main/java/org/apache/kafka/tools/ManifestWorkspace.java