BorderSide constructor

const BorderSide({Color color: const Color(0xFF000000), double width: 1.0, BorderStyle style: BorderStyle.solid })

Creates the side of a border.

By default, the border is 1.0 logical pixels wide and solid black.

Implementation 

const BorderSide({
  this.color = const Color(0xFF000000),
  this.width = 1.0,
  this.style = BorderStyle.solid,
}) : assert(color != null),
     assert(width != null),
     assert(width >= 0.0),
     assert(style != null);