"Ukrainian officials were asking for a meeting with Trump for along time. As I remember, it was a clear fact that Trump wants to meet only if Biden case will be included,” said Serhiy Leshchenko, an anti-corruption advocate and former member of Ukraine's Parliament, who had been a former adviser to Zelenskiy but has recently been distanced from the administration. "This issue was raised many times. I know that Ukrainian officials understood."
Asked if it had been understood as a condition, Leshchenko said, "Yes."
http://abcnews.go.com/Politics/ukrainians-understood-biden-probe-condition-trump-zelensky-phone/story?id=65863043