I guess the email to Trump Jr. just gave a link to already public knowledge about Wikileaks emails:
A 2016 email sent to President Trump and top aides pointed the campaign to hacked documents from the Democratic National Committee that had already been made public by the group WikiLeaks a day earlier.
[….]The full email — which was first described to CNN as being sent on Sept. 4, 10 days earlier — indicates that the writer may have simply been flagging information that was already widely available.