BorderRadius.only constructor

const BorderRadius.only({Radius topLeft: Radius.zero, Radius topRight: Radius.zero, Radius bottomLeft: Radius.zero, Radius bottomRight: Radius.zero })

Creates a border radius with only the given non-zero values. The other corners will be right angles.

Implementation 

const BorderRadius.only({
  this.topLeft = Radius.zero,
  this.topRight = Radius.zero,
  this.bottomLeft = Radius.zero,
  this.bottomRight = Radius.zero,
});