I have a grammar with rules named xif and xcontinue and others, which were renamed from if/continue/etc due to antlr creating variables with these names and clashing with java. It would be more polished if antlr distinguished its identifiers from any possible back-end reserved words somehow.
A consistent prefixing scheme might suffice, preventing clashes but keep a human-comprehensible correspondence between the parser and the generated back-end code (perhaps have the prefix 'ANTLR4_' as a reserved prefix for antlr itself?).