@Override
            public String toString() {
                return MoreObjects.toStringHelper(this)
                                  .add("type", type)
                                  .add("value", value)
                                  .toString();
            }
Collects {@link PathVariable}s from the parsed {@link PathSegment}s.
grpc/src/main/java/com/linecorp/armeria/server/grpc/HttpJsonTranscodingService.java