code: public OAuth.OAuthToken requestJWTApplicationToken(String clientId, java.util.List<String>scopes, byte[] rsaPrivateKey, long expiresIn) throws IllegalArgumentException, IOException, ApiException {
      return this.requestJWTUserToken(clientId, null, scopes, rsaPrivateKey, expiresIn);
    }
docs: <b>RESERVED FOR PARTNERS</b> Request JWT Application Token
  Configures the current instance of ApiClient with a fresh OAuth JWT access token from DocuSign
  @param clientId DocuSign OAuth Client Id (AKA Integrator Key)
  @param scopes the list of requested scopes. Values include {@link OAuth#Scope_SIGNATURE}, {@link OAuth#Scope_EXTENDED}, {@link OAuth#Scope_IMPERSONATION}. You can also pass any advanced scope.
  @param rsaPrivateKey the byte contents of the RSA private key
  @param expiresIn number of seconds remaining before the JWT assertion is considered as invalid
  @return OAuth.OAuthToken object.
  @throws IllegalArgumentException if one of the arguments is invalid
  @throws IOException if there is an issue with either the public or private file
  @throws ApiException if there is an error while exchanging the JWT with an access token