Valo theme on Vaadin 8 compiled using jdk11 produces question marks for neg

I’ve run into a problem when changed to use jdk11 to compile theme. It seems that negative decimal values is sass produces incorrect css.

For example; There is setting in filterselect scss @mixin valo-combobox-button-style

margin-top: -.47em;

and when compiled using jdk11 this generates css-line

margin-top: ?0.47em;

Using jdk8 this value was correctly

margin-top: -0.47em;

If similiar value is used in own selector, it can be fixed using syntax

margin-top: -#{.47em};

Tried with Vaadin 8.9.4, AdoptOpenJDK 11.0.5, Apache Maven 3.5.3


I do not remember by hard now, is it possible to change the command line parameters of the SASS compilation, but if it is, it looks like “-release 8” parameter is needed there, so that jdk11 would compile it in Java 8 mode.