code: public static ManagedChannel fromOfflineAuth(OfflineAuth auth, String fields)
        throws IOException, GeneralSecurityException {
      return fromCreds(auth.getCredentials(), fields);
    }
docs: Create a new gRPC channel to the Google Genomics API, using either OfflineAuth
  or the application default credentials.
  
  This library will work with both the newer and older versions of OAuth2 client-side support.
  
  https://developers.google.com/identity/protocols/application-default-credentials
  
  @param auth The OfflineAuth object.
  @param fields Which fields to return in the partial response, or null for none.
  @return The ManagedChannel.
  @throws IOException
  @throws GeneralSecurityException