private Map.Entry<String, JsonNode> findAuthNode(final JsonNode config, final String reposName) {
        final JsonNode auths = config.get("auths");
        if (auths != null && auths.size() > 0) {
            final Iterator<Map.Entry<String, JsonNode>> fields = auths.fields();
            while (fields.hasNext()) {
                final Map.Entry<String, JsonNode> entry = fields.next();
                if (entry.getKey().endsWith("://" + reposName) || entry.getKey().equals(reposName)) {
                    return entry;
                }
            }
        }
        return null;
    }
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