@Override
        public String toString() {
            return "Comma-separated header rules, where each header rule is of the form "
                    + "'[action] [header name]:[header value]' and optionally surrounded by double quotes "
                    + "if any part of a header rule contains a comma";
        }
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