Setting TreeMap Values

Problem:
I want the color start to be red for values below 0 and green for values above 0 i.e. if the values are negative or < 0 then transition in shades of red and if values are > 0 then transition in shades of green.

Answer:
Unfortunately, we can't set Treemap colors for values below zero(0) so all values should be above zero as you can see in this demo.