@Override
        public String toString() {
            return MoreObjects.toStringHelper(this)
                              .add("path", path)
                              .add("index", index)
                              .add("pathVarIndex", pathVarIndex)
                              .toString();
        }
Parses 'Variable' part.

<p>
Variable = "{" FieldPath [ "=" Segments ] "}"
</p>
grpc/src/main/java/com/linecorp/armeria/server/grpc/HttpJsonTranscodingPathParser.java