Github user danielsun1106 commented on the pull request:
https://github.com/apache/groovy/commit/7e7b508c02bf35e72fca1efcb7cc0d8a4f25038a#commitcomment-28347747
In src/antlr/GroovyLexer.g4:
If we do not like `'''1234''''''`, we can forbid it by lexer. To be honest,
I don't care about it because few developers will write code like that IMO...---
