I have never heard of this lad but there are news reports just appearing that he has come to Cardiff from Shamrock Rovers on loan (loan period not specified yet).

He seems to be a highly regarded midfielder - aged 18 or 19 depending on which report you read - and is part of the Ireland u21 squad.

https://www.rte.ie/sport/soccer/2019...rdiff-on-loan/

http://leagueofireland.ie/index.php/...-cardiff-city/

https://www.the42.ie/aaron-bolger-ca...76142-Feb2019/

This looks like a first team addition, not u23/DVP - and presumably can be used on top of the 25 because of his age?