public boolean hasManifest(PluginType type, String className) {
            return manifests.values()
                    .stream()
                    .map(m -> m.get(type))
                    .anyMatch(s -> s.contains(className));
        }
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