It should be bridged for 5V Pro Micro. Without the solder bridge cheap Pro Micro spit out only 4.6V instead of 5V at both VCC and RAW pin in my test. This is due to forward voltage drop of protection ...

This repo is a derivation of https://github.com/jonatanolofsson/maple-bootloader (mini-boot branch) which is in turn a derivation of the maple-bootloader created by ...