Generated golang parser has syntax error

[Jason Gu]

I tried to use antlr-4.8-complete.jar to generate java9 lexer and parser in golang.
I used the Java.g4 downloaded from https://github.com/antlr/grammars-v4/blob/master/java/java9/Java9.g4 and ran the command:

antlr4 -Dlanguage=Go Java9.g4

I got 4 go files including java9_lexer.go

But I found there exists syntax errors in java9_lexer.go:

And I can't compile this file:

Anyone here can help?