xtext - Auto format with my own xText DSL changes the order of elements

Question

To customize auto formating in my xText Project I edited my subclass of AbstractDeclarativeFormatter. That works like a charm but the elements are in a completely different order than in my xText grammar file. How can I configure my desired order of elements for auto formating?

EDIT: I just noticed the order only changes when I call the auto formatter from the command line with

    Builder builder = SaveOptions.newBuilder();
    builder.format();
    SaveOptions s = builder.getOptions();

    ByteArrayOutputStream output = new ByteArrayOutputStream();
    try {
        rootOfXtextAst.eResource()
                .save(output, s.toOptionsMap());
        String text = output.toString();

        return text;
    } catch (IOException e) {
        [...]
    }