UpDropDown constructor
      const
      UpDropDown({ 
    
    
- Key? key,
- String? value,
- bool readOnly = false,
- UpValidation? validation,
- required List<UpLabelValuePair> itemList,
- ValueChanged<String?> ? onChanged,
- UpStyle? style,
- UpColorType? colorType,
- UpInputType? type,
- String? label,
- String? hint,
- List<String> ? values,
- Widget? prefixIcon,
- EdgeInsets? contentPadding,
- ValueChanged<List< ? onMultipleChanged,String> ?>
- bool isMultipleSelect = false,
Implementation
const UpDropDown({
  Key? key,
  this.value,
  this.readOnly = false,
  this.validation,
  required this.itemList,
  this.onChanged,
  this.style,
  this.colorType,
  this.type,
  this.label,
  this.hint,
  this.values,
  this.prefixIcon,
  this.contentPadding,
  this.onMultipleChanged,
  this.isMultipleSelect = false,
}) : super(key: key);