@Override
	public void discoverLexerRule(RuleAST rule, GrammarAST ID, List<GrammarAST> modifiers, GrammarAST options,
								  GrammarAST block)
	{
		checkInvalidRuleDef(ID.token);

		if (modifiers != null) {
			for (GrammarAST tree : modifiers) {
				if (tree.getType() == ANTLRParser.FRAGMENT) {
					inFragmentRule = true;
				}
			}
		}

		if (!inFragmentRule) {
			nonFragmentRuleCount++;
		}
	}
Value of caseInsensitive option (false if not defined)
tool/src/org/antlr/v4/semantics/BasicSemanticChecks.java