There are at least two generators now: "Official" Antlr Tool jar 4.13.2, and "antlr-ng". There are others that are tied into the runtime tightly, e.g., "Antlr4cs" and "Antlr4ng", both of which use a modified "Official" Antlr tool jar.

We need to do this because Antlr-ng now can generate parsers for "Official" Antlr runtimes.