Support null-safety

[amitkot]

Hi,

I created a PR for supporting null-safety:
#18

I later saw that there is also #17 waiting in the PR queue.

[rafaelmaeuer]

So there are already two PRs addressing this issue @mendieta @a-guerrero any plans to merge them?

[rafaelmaeuer]

In the meantime there are 3 PRs addressing null-safety, @a-guerrero @mendieta any further plans on maintaining this library??? Otherwise it might be worth handing it over to e.g. @NarHakobyan???

[omidraha]

Please merge PR.