Synonyms of "possibly empty (value)"?

The antonyms of ‘non-empty’ could be:

1. Empty
2. Possibly empty

But I had not see it is being frequently used as "non-nullable", so I suspect there are some other synonyms of "possibly empty" exists. Why I find it I is ambiguity of "Possibly empty array". It could mean:

1. Empty or non-empty array
2. Empty or non-empty array, or anything else, e. g. string or number