Unlike @jetti and @mindcrime, I would use the opportunity of a green fields project to switch to and learn a more suitable industry-accepted language such as Python instead of a declining language that I happen to know better like the ageing Apache Groovy, which was originally optimized for scripting but badly retrofitted with static typing and for building systems, which other languages built from the ground up for such stuff are markedly better at, such as Java, Scala, and Kotlin on the JVM at least.