The Lindt cafe manager invited Henry and his family to visit him in Martin Place and collect a bag of Easter goodies he'd had specially made for them.

And so one day in April, Mercedez Hinchcliff and her children, Henry and Kate, set off from their home in Wollongong for the ultimate chocolate experience.

"It's definitely something that stuck out in his mind as being one of his best days," Mrs Hinchcliff said of her six-year-old son, who has a rare disease that limits his diet to fewer than 50 foods.

"It taught him that people go out of their way for people."

It was the only time Mrs Hinchcliff met Mr Johnson, 34, who was killed in the siege on his cafe, but the kindness he showed her family on that day has stuck with her.

It began when Mrs Hinchcliff's friend Hayley Rowney got in touch with Mr Johnson and explained Henry's condition - eosinophilic esophagitis.

"There are so many foods [Henry] can't eat," Mrs Hinchcliff said of her son.

"He can actually have chocolate - the Lindt 85 per cent is the only one he can have in the world, but they don't make an Easter egg out of it.

"[Mr Johnson] said, 'no problem, we'll make you one'. They made a huge one, and when they found out my daughter couldn't have dairy, they actually made her one as well," Mrs Hinchcliff said.

"They told my friend Hayley it would take quite a while to make because it would need so much chocolate."

Just before Easter, Mrs Hinchcliff and Mrs Rowney took their children to Sydney to collect their surprise chocolate bounty.

Mrs Hinchcliff said Mr Johnson was "really happy" as he presented Henry and Kate with their eggs, and insisted they take photos of the occasion.

The eggs were "huge, and really intricate, obviously hand-made".

While Kate, 3, may not hold on to clear memories of her first Easter egg, Henry brings it up all the time.

Mrs Hinchcliff said she was heartbroken when she found out that Mr Johnson was among the victims of the Lindt cafe siege. She hoped his parents, Australian artist Ken Johnson and his former wife Rowen,  would take some comfort by hearing of their son's kind gesture towards her children.

:We are devastated to hear of his passing and wish to pass along our appreciation of him and our deepest condolences to his family. We will always remember him fondly."

Mr Johnson's parents released a statement via journalist Ben Fordham earlier on Tuesday, saying: "We are so proud of our beautiful boy Tori, gone from this earth but forever in our memories as the most amazing life partner, son and brother we could ever wish for".

Mr Johnson had worked at the Lindt cafe since October 2012, and, before that, had worked at a host of restaurants in Sydney and the United States.

His family has gathered at the 34-year-old's Redfern apartment, His brother James is flying to Sydney from Canada.

It is understood the cafe manager's partner of 14 years, Thomas Zinn, is being comforted along with the Johnsons at the couple's home.

Friends of Mr Johnson described him on Tuesday as "a loving, placid and very gentle soul ... a true gentleman".

Deputy Police Commissioner Catherine Burn would not comment on Tuesday about claims that Mr Johnson was shot when he tried to wrestle the weapon from Monis, to allow the other hostages to escape.