assert Debug.log("java mirror", Debug.show(symbol) + " -> " + mirror);
assert Debug.log("java mirror: ", symbol, " -> ", mirror);
    public Field getField(Symbol symbol) {        Object value = fields.get(symbol);        if (value != null) return (Field)value;        Field mirror = getField0(symbol);        assert Debug.log("java mirror", Debug.show(symbol) + " -> " + mirror);        fields.put(symbol, mirror);        return mirror;    }