Here's a stumper. What do you do when an undercover FBI agent allegedly arranges for $20,000 to be donated to your campaign, quite possibly in violation of campaign finance laws, but the feds won't help you figure out if you really got the money, or who gave it to you? That's pretty much the situation Mayor Ed Lee's campaign finds itself in after a recent court filing by a defense attorney in the complex public corruption case of suspended state Sen.