The ZIP file may contain other files and directories that are
               created using the  flutter create  command, such as
               pubspec.yaml; it may also include asset files
               (e.g. images, fonts) or data. We recommend running
               flutter clean before creating the ZIP file to
               strip out unnecessary binaries.

With the exception of packages (see below), all executable content
               must be included in the ZIP file.

All code needed to load and execute the application must be
               written in Dart, with the exception of any packages
               (as mentioned below).

Dart code must appear in a file that has a filename ending in
               .dart. The total size of all Dart files in the ZIP
               file, excluding unit tests that are not executed, must be no
               more than 5,120 bytes as (for example) measured by the
               command find . -name "*.dart" | xargs cat | wc -c.