static List<PathVariable> from(List<PathSegment> segments,
                                       PathSegment.PathMappingType type) {
            return segments.stream()
                           .filter(VariablePathSegment.class::isInstance)
                           .flatMap(segment -> resolvePathVariables(null, (VariablePathSegment) segment, type)
                                   .stream())
                           .collect(toImmutableList());
        }
Collects {@link PathVariable}s from the parsed {@link PathSegment}s.
grpc/src/main/java/com/linecorp/armeria/server/grpc/HttpJsonTranscodingService.java