Whistleblower Protection Act of 2019 This bill retroactively prohibits a federal contractor from taking certain personnel actions with respect to specified employees. Specifically, the bill prohibits a federal contractor from taking a personnel action against an employee who has lawfully disclosed information the employee reasonably believes shows (1) a violation of any law, rule, or regulation; or (2) gross mismanagement, waste of funds, abuse of authority, or substantial and specific danger to public health or safety. Further, a federal contractor may not take a personnel action against an employee because of the employee's (1) lawful exercise of an appeal, complaint, or grievance right, or testifying or assisting in the exercise of such right; (2) cooperation with or disclosure of information to the agency's inspector general or special counsel; or (3) refusal to obey an order that would require the individual to violate a law, rule, or regulation. A federal agency is prohibited from pressuring a federal contractor from taking any personnel action against an employee based on such disclosures or actions by the employee.