code: public String getAuthToken(GetIamAuthTokenRequest request) throws AmazonClientException {
          DefaultRequest<Void> signableRequest = new DefaultRequest<Void>(SERVICE_NAME);
          signableRequest.setResourcePath("/");
          setEndpoint(signableRequest, request);
          setParameters(signableRequest, request);
          signableRequest.setHttpMethod(HttpMethodName.GET);
          return presignerFacade.presign(signableRequest, getExpirationDate()).toExternalForm().replaceFirst("http://", "");
      }
docs: Create an authorization token used to connect to a database that uses RDS IAM authentication.