src/File.php
public function getType(bool $withEncoding = false): string
    {
        $this->checkFileReadPermissions();

        if (null !== $mime = $this->storage->getFileType($withEncoding)) {
            return $mime;
        }

        throw new UnexpectedValueException('unable to determin files content-type', 500);
    }
public function getType(bool $withEncoding = false): string
    {
        $this->checkFileReadPermissions();

        if (null !== $mime = $this->storage->getFileType($withEncoding)) {
            return $mime;
        }

        throw new UnexpectedValueException('unable to determin files content-type', 500);
    }
guess content-type (mime) of storage
@param  bool $withEncoding
@return string
@throws UnexpectedValueException|FileNotFoundException|AccessDeniedException