How to insert a Libreoffice writer Annotation with a date using Python

Question

Please note, this is a self answered question for reference.
Most of the references to com.sun.star.text.textfield.Annotation refer to Date as being a :: com :: sun :: star :: util :: reference but no end of fiddling about with the contents will actually create an annotation with a date.
Setting Date.Year, Date.Month and Date.Day will appear successful but the annotation itself still appears without a date i.e.

anno = model.createInstance("com.sun.star.text.textfield.Annotation")
anno.Content = "this is my annotation/comment"
anno.Author = doc.DocumentProperties.Author
anno.Date.Year = 2020
anno.Date.Month = 5
anno.Date.Day = 18

Answer 1

The documentation is not always complete, or is not obvious, depending upon where you look.
For LibreOffice 6.0 https://api.libreoffice.org/docs/idl/ref/Annotation_8idl_source.html
The Annotation.idl is described as:

 service  com::sun::star::text::TextField;
 [property]string Author;
 [optional, property]string Initials;
 [optional, property]string Name;
 [property]string Content;
 [property]com::sun::star::util::Date Date;
 [optional, property]com::sun::star::util::DateTime DateTimeValue;

The key here is the optional DateTimeValue which it would appear is the item that needs to be set to provide the Annotation with a Date and Time.
DateTimeValue structure is from com.sun.star.util.DateTime
To create an annotation (with a date and time) in a writer document using a python script, use the following as a template.

from uno import createUnoStruct
import time

def fs_Annotation(*args):
    #get the doc from the scripting context which is made available to all scripts
    desktop = XSCRIPTCONTEXT.getDesktop()
    model = desktop.getCurrentComponent()
    try:
        text = model.Text
    except:
        # The macro has been called externally but LibreOffice was not running at the time
        return None
    tRange = text.End
    cursor = desktop.getCurrentComponent().getCurrentController().getViewCursor()
    doc = XSCRIPTCONTEXT.getDocument()
    # you cannot insert simple text and text into a table with the same method
    # so we have to know if we are in a table or not.
    # oTable and oCurCell will be null if we are not in a table
    oTable = cursor.TextTable
    oCurCell = cursor.Cell

    anno = model.createInstance("com.sun.star.text.textfield.Annotation")

    anno.Content = "this is my annotation/comment"
    #Use documents author
    #anno.Author = doc.DocumentProperties.Author
    #Use hardcoded text
    anno.Author = "Joe Bloggs"

    t = time.localtime()
    dtv=createUnoStruct("com.sun.star.util.DateTime")
    dtv.Year = t.tm_year
    dtv.Month = t.tm_mon
    dtv.Day = t.tm_mday
    dtv.Hours = t.tm_hour
    dtv.Minutes= t.tm_min
    dtv.Seconds = t.tm_sec
    dtv.NanoSeconds = 0
    anno.DateTimeValue = dtv

    if oCurCell == None:    # Inserting into text
        text.insertTextContent(cursor, anno, True)
    else:                   # Inserting into a table
        oCurCell.insertTextContent(cursor, anno, False)
    return None