...The GremlinClient library accepts both a GremlinServer object as well as a webSocketConfiguration object that contains a custom configuration set for establishing the WebSocket connection to Amazon Neptune. The SigV4RequestSigner library fetchs IAM credentials using the FallbackCredentialsFactory API (which works similarly to the Java Default Credential Provider Chain), performs the proper Signature Version 4 signing of an http request, and creates the proper WebSocket configuration based on this signed http request. One can then pass this webSocketConfiguration to the GremlinClient to create the connection to Neptune.