I can't imagine what that is, unless you are referring to the Alexandra Chalupa allegations... which outside of an article that ran in Politico, remain unsupported. And what was ever done to bring forth the whistleblower is not germane to the question of whether or not Trump did withhold the military aid from the Ukraine so he could leverage it against Zelensky's willingness to perform a political favor for him. If it happened? It might look bad for a while, but it wouldn't exonerate Trump.
I would gladly offer up the Bidens, Schiff, Alexandra Chalupa and the whistleblower if it meant getting Rudy Giuliani, Robert Hyde, John Bolton, Rick Perry, Devin Nunes, Mick Mulvaney and Mike Pompeo on the stand.