: null,
      style: style,
    ));

    // Getting the value of size throws an exception unless hasSize is true.
    properties.add(DiagnosticsProperty&lt;Size&gt;.lazy(
      'size',
      () =&gt; size,
      description: '${ hasSize ? size : "MISSING" }',
    ));

    // If the `toString` method for the property value does not provide a
    // good terse description, write a DiagnosticsProperty subclass as in
    // the case of TransformProperty which displays a nice debugging view
    // of a Matrix4 t