Use a custom aws endpoint

I have a running [localstack](https://github.com/localstack/localstack) server, I want to update the sample.properties file to point to another endpoint, for example: `http://localhost:4456`
Can anyone help me?

Start by locating the sample.properties file and checking how its endpoint settings are consumed by the Node.js client. Configure the sample to accept an endpoint such as http://localhost:4456, then verify that the localstack-backed sample connects using that value.

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