@classmethod
def find_namespace_packages(cls, packages):
    """Find packages that are created by multiple components."""
    namespace_packages = set()
    seen_packages = set()
    for toplevel_packages in packages.values():
        for package in toplevel_packages:
            if package in seen_packages:
                namespace_packages.add(package)
            else:
                seen_packages.add(package)
    namespace_packages = sorted(namespace_packages)
    return namespace_packages
