How do I set author value on a new markup annotation?

Q: Hi, I’m creating some Text annotations and am unclear on how to add
an author value. When I view a PDF in Acrobat and right-click on an
annotation a Properties dialog appears. In the General Tab there is
an Author textbox. Is it possible to be able to populate the field
programmatically with PDFNet?
A: You can use SetTitle() method that is available for all annotation
types derived from Markup.

SetTitle() method effectively populates the ‘T’ field of the
annotation dictionary object, which is used to identify the author of
the annotation. From the PDF standard:

T text string (Optional; PDF 1.1) The text label that shall be
displayed in the title bar of the annotation’s pop-up window when open
and active. This entry shall identify the user who added the