in src/setter/mixed-setter/index.tsx [265:274]
private handleInitial({ initialValue }: SetterItem, fieldValue: string) {
const { field, onChange } = this.props;
let newValue: any = initialValue;
if (newValue && typeof newValue === 'function') {
newValue = newValue(field);
} else if (fieldValue) {
newValue = fieldValue;
}
onChange && onChange(newValue);
}