An associate of Rep. Matt Gaetz (R-Fla.) on Monday pleaded guilty to child sex trafficking and other charges while agreeing to cooperate fully with U.S. prosecutors investigating other persons. Magistrate Judge Leslie Hoffman accepted the guilty plea from Joel Greenberg, the former tax collector for Seminole County in Florida, at federal court in Orlando. The court “found the facts sufficient to allow the defendant to plead guilty” after Greenberg acknowledged that he signed an 86-page plea agreement and admitted to the facts set forth in the document. Greenberg, who was placed in the custody of U.S. Marshals pending sentencing, was associated with Gaetz, who in 2017 promoted him as a potential congressional nominee. Greenberg, he said, had “been a disruptor” at the Seminole County Tax Collector’s Office. Gaetz’s office did not respond to an inquiry. The congressman has said in response to news reports about federal investigators probing him that …