code: public static CallCredentials basicAuth(final String username, final String password) {
          final Metadata extraHeaders = new Metadata();
          extraHeaders.put(AUTHORIZATION_HEADER, encodeBasicAuth(username, password));
          return new StaticSecurityHeaderCallCredentials(extraHeaders);
      }
docs: Creates a new call credential with the given username and password for basic auth.
  
  <p>
  <b>Note:</b> This method uses experimental grpc-java-API features.
  </p>
  
  @param username The username to use.
  @param password The password to use.
  @return The newly created basic auth credentials.