resolveEndpointUrl

Attempts to find the configured endpoint URL for a specific service.

We look at the following sources in-order:

1. The value provided by a service-specific environment setting:

1. The environment variable AWS_ENDPOINT_URL_${SNAKE_CASE_SERVICE_ID}.

2. The JVM system property aws.endpointUrl${JavaSDKClientPrefix}.

2. The value provided by the global endpoint environment setting:

1. The environment variable AWS_ENDPOINT_URL.

2. The JVM system property aws.endpointUrl.

3. The value provided by a service-specific parameter from a services definition section in the shared configuration file (${snake_case_service_id}.endpoint_url).

4. The value provided by the global parameter from a profile in the shared configuration file (endpoint_url).

Endpoint URL settings can be disabled globally through either the environment or shared config, in which case the above list of sources is ignored.