For the example:
ref over A
[[http://www.google.com GOOGLE]]
end ref
The REF box renders empty. But when we add any non-space character(s) before or after the linking braces, then the LINK will appear inside the REF box with said extra characters.
I am using plantuml.1.2019.4.jar
I also tested it here: https://www.planttext.com/, http://plantuml.com/
