optimize capacity & add assert messages in GeoJson

[wjdqhry]

I found that initial capacity of ArrayList is set to smaller than that actually needed, and in some cases, it isn't set at all.
Additionally, while LineString and MultiPoint use assertions for validating parameters, but Polygon doesn't.

I created this issue for fix it.

I can see this code was copied from Spring Data MongoDB, and still remains unchanged.
I'll trying to fix that too after resolve this issue.

Thank you.