code: void revokeUnauthToken(HeaderToken oldToken) {
      synchronized (lock) {
        if (headerCache.getToken() == oldToken) {
          LOG.warn("Got unauthenticated response from server, revoking the current token");
          headerCache = EMPTY_HEADER;
        } else {
          LOG.info("Skipping revoke, since the revoked token has already changed");
        }
      }
    }
docs: Clear the cache.
  
  @param oldToken for a comparison.  Only revoke the cache if the oldToken matches the current one.