private static RegisterSpecList concatenate(Local<?> first, Local<?>[] rest) {
    int offset = (first != null) ? 1 : 0;
    RegisterSpecList result = new RegisterSpecList(offset + rest.length);
    if (first != null) {
      result.set(0, first.spec());
    }
    for (int i = 0; i < rest.length; i++) {
      result.set(i + offset, rest[i].spec());
    }
    return result;
  }
true once we've fixed the positions of the parameter registers
android/android_framework/dex-maker/src/main/java/com/android/dx/Code.java