A family member was reluctant to talk about Mr Williams' death yesterday, but indicated he was not known to have suffered any serious medical condition.
"So this was a shock to everyone," she said. That included his twin brother, Jesse Williams.
Waiheke's senior police officer was on leave yesterday, and no one else was available to provide details of the case, although it is believed to have been referred to a coroner.
Placemakers Waiheke owner Lee Stickland said last night that Mr Williams was a fairly frequent visitor to the store and well-liked.
"He was well-known in the community and a much loved young chap.
"It will be a very sad occasion tomorrow," a still shaken Mr Stickland said in reference to this afternoon's tangi, which is due to start at 1.30pm. "It's very sad because somebody so young has lost his life while making his way in the world. You don't expect that - that's the shocking thing.
"I understand he had made a lot of progress in his apprenticeship."
Mr Stickland said two of his staff tried to revive the young man using CPR before the paramedics arrived. He closed the yard for the rest of the day, sending his 15 or so staff home out of respect for Mr Williams.
He did not believe Mr Williams was loading building materials at the time of his collapse, or doing any other strenuous activity.
"I believe he was just walking about."