semanticsBuilder property Null safety
Returns a function that builds semantic information for the picture drawn by this painter.
If the returned function is null, this painter will not contribute new SemanticsNodes to the semantics tree and the CustomPaint corresponding to this painter will not create a semantics boundary. However, if the child of a CustomPaint is not null, the child may contribute SemanticsNodes to the tree.
SemanticsBuilderCallback? get semanticsBuilder => null;