How to specify a target package for ANTLR?

ANTLR provides a header tool which allows you to include package and imports. You include this in your *.g grammar file:

@header {
    package org.xmlcml.cml.converters.antlr;
    import java.util.HashMap;
}

And you may need it in the Lexer as well:

@lexer::header {package org.xmlcml.cml.converters.antlr;}

and in case you need to add some members and code:

@members {
    HashMap<String, Object> objectMap = new HashMap<String, Object>();
    //...

    private void addArrayValue(String content) {
    //... code required by snippets in the grammar

    }
}