obscuringCharacter property
Character used for obscuring text if obscureText is true.
Must have a length of exactly one.
Implementation
String get obscuringCharacter => _obscuringCharacter;Implementation
set obscuringCharacter(String value) {
  if (_obscuringCharacter == value) {
    return;
  }
  assert(value.characters.length == 1);
  _obscuringCharacter = value;
  markNeedsLayout();
}