How to access simple-method map with integer keys

Does anyone know how to access simple-method maps with integer keys?

So if I have parameters = quantityFromMap={3=, 2=3, 10=, 1=1, 7=, 6=,
5=, 4=, 9=, 8=}

I'm not able to access the one of the mapped values using
${parameters.quantityFromMap.1}.

I think the problem has to do with the integer key. I've faced this
problem in the past and ended up including the underscore before the
number indexes just so they would be considered string keys.