@Override
    String allRequiredBitmask(
        ImmutableList<Property> trackedProperties, int bitBase, int remainingBits) {
      // We have to be a bit careful with sign-extension. If we're using a byte and
      // the mask is 0xff, then we'll write -1 instead. The comparison set$0 == 0xff
      // would always fail since the byte value gets sign-extended to 0xffff_ffff.
      // We should also write -1 if this is not the last field.
      boolean minusOne = remainingBits >= 32 || remainingBits == 16 || remainingBits == 8;
      return minusOne ? "-1" : hex((1 << remainingBits) - 1);
    }
Subclass for when there are no Kotlin default properties.
value/src/main/java/com/google/auto/value/processor/BuilderRequiredProperties.java