presto-main/src/main/java/io/prestosql/server/remotetask/HttpLocationFactory.java/HttpLocationFactory/createStageLocation
class HttpLocationFactory:    @Override
    public URI createStageLocation(StageId stageId)
    {
        requireNonNull(stageId, "stageId is null");
        return uriBuilderFrom(baseUri)
                .appendPath("v1/stage")
                .appendPath(stageId.toString())
                .build();
    }