padding property
The amount to pad the child in each dimension.
If this is set to an EdgeInsetsDirectional object, then textDirection
must not be null.
Implementation
@override
EdgeInsets get padding {
  EdgeInsets insets = EdgeInsets.only(
      left: paddingLeft.computedValue,
      right: paddingRight.computedValue,
      bottom: paddingBottom.computedValue,
      top: paddingTop.computedValue);
  assert(insets.isNonNegative);
  return insets;
}