uploadMimeTypes top-level constant
MIME types the gateway accepts (the same list as the server's upload allow-list).
Implementation
const Set<String> uploadMimeTypes = {
'image/png', 'image/jpeg', 'image/gif', 'image/webp', 'image/heic', 'image/heif', //
'application/pdf', 'text/plain', 'text/csv', 'application/zip',
'application/msword', 'application/vnd.openxmlformats-officedocument.wordprocessingml.document',
'application/vnd.ms-excel', 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet',
'video/mp4', 'audio/mp4', 'audio/mpeg',
};