Is it possible to use URL hyperlinks in Key-Value pairs?

Is it possible to use URL hyperlinks in Key-Value pairs (MapAnnotation)?
I could not, but the readme file of OMERO.mapr shows apparent hyperlinks (text in blue), so I wonder if it's possible or not. https://github.com/ome/omero-mapr
I could not, but the readme file of OMERO.mapr shows apparent hyperlinks (text in blue), so I wonder if it's possible or not. https://github.com/ome/omero-mapr