isAbsoluteUri function
Whether value is an absolute URI under RFC 3986's generic syntax
(scheme ":" hier-part …) — the check the uri format uses. Unlike
Uri.tryParse, it does not treat data: (or any scheme) specially, so
data://config and other custom-scheme resource URIs are accepted.
Implementation
bool isAbsoluteUri(String value) => JsonSchemaValidator._isUri(value);