Difference between Antlr 3 and Antlr 4 in handling of extra parentheses in grammar

[Jim Sculley]

Is there a reason why Antlr4 rejects superfluous parentheses surrounding groups whereas Antler 3 accepts them?  For example:

grammar Test;
testRule: THING;
THING : 'A' ~(('A'))*;

Antlr 4 will fail with the following:

error(50): Test.g:3:14: syntax error: '(' came as a complete surprise to me while looking for lexer rule element
error(50): Test.g:3:19: syntax error: mismatched input ')' expecting SEMI while matching a lexer rule

The extra parentheses seem harmless to me (a relative novice) but perhaps there is a valid reason that Antlr4 flags it as an error.