private String effectiveRegistryName(DockerImageName dockerImageName) {
        final String registry = dockerImageName.getRegistry();
        if (!StringUtils.isEmpty(registry)) {
            return registry;
        }
        return StringUtils.defaultString(
            DockerClientFactory.instance().getInfo().getIndexServerAddress(),
            DEFAULT_REGISTRY_NAME
        );
    }
Looks up an AuthConfig for a given image name.
<p>
Lookup is performed in following order, as per
https://docs.docker.com/engine/reference/commandline/cli/:
<ol>
    <li>{@code credHelpers}</li>
    <li>{@code credsStore}</li>
    <li>Hard-coded Base64 encoded auth in {@code auths}</li>
    <li>otherwise, if no credentials have been found then behaviour falls back to docker-java's
    implementation</li>
</ol>

@param dockerImageName image name to be looked up (potentially including a registry URL part)
@param defaultAuthConfig an AuthConfig object that should be returned if there is no overriding authentication available for images that are looked up
@return an AuthConfig that is applicable to this specific image OR the defaultAuthConfig.
core/src/main/java/org/testcontainers/utility/RegistryAuthLocator.java