Some requests return a list with the value null inside

[chrisbartoloburlo]

This happens for both v1 and v2:

When sending a request for a country via a non-existent alpha code we get [null], rather than just the empty list [].

curl -v \
  --url 'http://localhost:8080/rest/v2/alpha?codes=QG' 

[amatosg]

this project is now dead :( as such, I forked it here