private void setParameters(DefaultRequest<Void> signableRequest, GetIamAuthTokenRequest request) {
        signableRequest.setParameters(ImmutableMapParameter.of(
                "DBUser", Collections.singletonList(request.getUserName()),
                "Action", Collections.singletonList("connect")));
    }
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