Mainly this comes from JPA Criteria queries doing:

criteriaBuilder.parameter(String.class, "1")

Because this is a "named paremeter" we render this as :1, but the Antlr grammars define named parameter support as COLON^ identifier, the identifier rule matches normal identifier syntax.

I tried adjusting the grammar rule to also match COLON^ INT_NUM, but that led to recognition failures (which i have not yet had time to triage). Another possibility is to render this as ?1 instead, though that has its own concerns.