What is in Trump's secret letter kept at the White House for Vance in case he's assassinated?

White House counterterrorism official Sebastian Gorka has revealed that Donald Trump has kept a secret letter in the Resolute Desk at the Oval Office in White House for JD Vance. The letter reportedly contains instructions for Vance in case Trump dies or is assassinated. This comes as Trump is visiting China after nine years, weeks after suffering an assassination attempt.