Answering my own question. It seems Discourse uses Moment.js format string. In the case of my request, it is simply a matter of changing h:mma and hmm a to HH:mm. More references on the Moment.js format page.
I hope I did not break things! 
Answering my own question. It seems Discourse uses Moment.js format string. In the case of my request, it is simply a matter of changing h:mma and hmm a to HH:mm. More references on the Moment.js format page.
I hope I did not break things!