void ngOnChanges(Map<String, SimpleChange> changes)

Source 

void ngOnChanges(Map<String, SimpleChange> changes) {
  if (this._isControlChanged(changes)) {
    setUpControl(this.form, this);
    this.form.updateValueAndValidity(emitEvent: false);
  }
  if (isPropertyUpdated(changes, this.viewModel)) {
    this.form.updateValue(this.model);
    this.viewModel = this.model;
  }
}