[TIMOB-19862] Semicolon in setUsername causes no username to be logged

Calling apm.setUsername("something;something") causes no username to be set in the performance monitoring. The crash logs have no username set and the username is unable to be found via search. I expected something other than it just not working to happen - an error when calling setUsername, the semicolon to be stripped out, or it to just work. For it to appear to work and then just absolutely do nothing is definitely frustrating. It took me a while to figure out what was wrong. Also, it is not documented that semicolons are not allowed in the username (probably because it was unintentional, I'm guessing).