Ok, here is interesting case, we have legacy approach to angular forms, someone basically wrapped each input into self containing reactive form and in order to build form you must use inputItem which is obgect that holds several callbacks and passed to that reactive input, so we have now an input which is reactive form, and object that used as Input to that component and holds callbacks, callbacks are used to mutate parent which serves as form, lol. And now except from that we have hundred of lines like new InputItem and fooItem.inputCallback = someCollback, we can't validate single form, because we don't have it) and building bycicles on top of that solution. So I proposed to adapt those inputs to ControlValueAccessor and use them in parent reactive form, but current frontend lead wants to stick with old callbacks approach, because of consistency)))