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://", "");
    }
Create an authorization token used to connect to a database that uses RDS IAM authentication.
aws-java-sdk-rds/src/main/java/com/amazonaws/services/rds/auth/RdsIamAuthTokenGenerator.java