CompositeData has no keys() method?

Set< String > keys = cData.getCompositeType().keySet();

StringBuffer writeCompositeData(StringBuffer buffer,
            String prefix, String name, CompositeData data) {
        if (data == null)
            return writeSimple(buffer,prefix,name,null,true);
        writeSimple(buffer,prefix,name,"CompositeData("+
                data.getCompositeType().getTypeName()+")",true);
        buffer.append(prefix).append("{").append("n");
        final String fieldprefix = prefix + " ";
        for (String key : data.getCompositeType().keySet()) {
            write(buffer,fieldprefix,name+"."+key,data.get(key));
        }
        buffer.append(prefix).append("}").append("n");
        return buffer;
    }

for (String key : data.getCompositeType().keySet()) {
    [...] data.get(key) [...];
}