public final Subclass withRegion(Regions region) {
        return withRegion(region.getName());
    }
Sets the region to be used by the client. This will be used to determine both the
service endpoint (eg: https://sns.us-west-1.amazonaws.com) and signing region (eg: us-west-1)
for requests. If neither region or endpoint configuration {@link #setEndpointConfiguration(EndpointConfiguration)}
are explicitly provided in the builder the {@link #DEFAULT_REGION_PROVIDER} is consulted.

<p> For regions not explicitly in the {@link Regions} enum use the {@link
#withRegion(String)} overload.</p>

@param region Region to use
@return This object for method chaining.
aws-java-sdk-core/src/main/java/com/amazonaws/client/builder/AwsClientBuilder.java