Thanks for letting me know.
I didn’t maintain the CoAP library because I didn’t think anyone was using it, and Particle API is based CoAP protocol so I think CoAP specified lib is no-needed
But I got to know that some developer try/want to use it, Okay I will maintain(compile/test) CoAP library for latest firmware.
We were interested in using COAP direct to our own web service for IOT transactions to reduce turnaround time (our use case has a , leaving the Particle channel for device management (firmware upgrades and heart beats).
I envisage a problem though - code size - we have not got much left…