@Override
        public String toString() {
            return "List of comma-separated URLs, ex: http://localhost:8080,https://localhost:8443.";
        }
Add the properties related to an internal-only server to the given {@link ConfigDef}.
@param configDef the {@link ConfigDef} to add the properties to; may not be null
connect/runtime/src/main/java/org/apache/kafka/connect/runtime/rest/RestServerConfig.java