default void close() throws IOException {
        // This method left intentionally blank.
    }
Lifecycle method to perform a clean shutdown of the retriever. This must
be performed by the caller to ensure the correct state, freeing up and releasing any
resources performed in {@link #init()}.

@throws IOException Thrown on errors related to IO during closure
clients/src/main/java/org/apache/kafka/common/security/oauthbearer/internals/secured/AccessTokenRetriever.java