Why ssl_session_cache_api:size is strictly positive instead of non_neg?

maxlapshin · June 17, 2024, 9:43am

erlang/otp/blob/master/lib/ssl/src/ssl_session_cache_api.erl#L156


      
          -doc(#{since => <<"OTP 19.3">>}).
          -doc """
          Returns the number of sessions in the cache.
          
          If size exceeds the maximum number of sessions, the current cache
          entries will be invalidated regardless of their remaining lifetime. Is
          to be callable from any process.
          """.
          -callback size(CacheRef) -> Size when
                CacheRef:: session_cache_ref(),
                Size :: pos_integer().
          
          -optional_callbacks([select_session/2, foldl/3]).

-callback size(CacheRef) -> Size when
      CacheRef:: session_cache_ref(),
      Size :: pos_integer().

Why zero is not allowed here?