marshaler: BuiltinMarshalingRoutines doesn't have the unmarshal method for BigDecimal

The generated code for the a BigDecimal field doesn't compile, example of the generated code InternalBlablablaMarshaling:
 ... 
private static void unmarshalAttributeTotal(JsonParser parser, ImmutableTicket.Builder builder)
      throws IOException {
    JsonToken t = parser.nextToken();
    BigDecimal value =
        unmarshal(parser, (BigDecimal) null, BigDecimal.class);
    builder.total(value);
  }
...