private static String validateUrl(String name, String url, SourceLocation location) {
        try {
            new URL(url);
            return url;
        } catch (MalformedURLException e) {
            throw new SourceException(String.format("Each externalDocumentation value must be a valid URL. "
                    + "Found \"%s\" for name \"%s\"", url, name), location);
        }
    }
Provides named links to external documentation.
smithy-model/src/main/java/software/amazon/smithy/model/traits/ExternalDocumentationTrait.java