What is "welshers"

Usage examples of "welshers".

He said welshers, no matter who they were, usually had a bad time of it, if I knew what he meant, and I did.

I crashed the eye, shooting it for no apparent reason except that it might find out where I was going, and he decided that whatever I was doing had to be a hell of a lot more interesting and important than strong-arming welshers for the Ginza, which was his main source of income at that point.