[antlr-interest] problem building json grammar maven2 + antlr3

[hanasaki]

Building json grammar below with the maven2 plugin for antlr3 and netbeans6
http://www.antlr.org/wiki/pages/viewpageattachments.action?pageId=819220
http://www.antlr.org/wiki/display/ANTLR3/Using+ANTLR+3+with+Maven+2

[antrun:run {execution: default}]
Executing tasks
     [java] ANTLR Parser Generator  Version 3.0 (May 17, 2007)  1989-2007
     [java] error(8):  file JsonTree.g contains grammar JSONTree; names
must be identical
     [java] error(3):  cannot find tokens file ./JSON.tokens
     [java] warning(138): JsonTree.g:0:0: grammar JSONTree: no start
rule (no rule can obviously be followed by EOF)