To be fair, the SIGMOD'15 conference was in June 2015 so the paper is only ~6 mos old. While it is based on Gremlin 2 rather than Gremlin 3, most all the code in the paper is SQL CET statements -- there's very little Gremlin. In Table 8 on the last page they show their code for the Gremlin->SQL CET translations, and only a few tweaks are needed to update the step names in column one to Gremlin 3.