how to update file name dynametically when upload in ionic 4

hi, i am using Ionic 4 with angilar 7 in my project. currently i am facing difficulties on upload image. it works fine with static name like

```
let options: FileUploadOptions = {
fileKey: 'file',
fileName: 'name.jpg',
headers: {}
.....
}
```

it working fine. but i need dynamic name. so i updated accordingly

```
this.temp_image_name = new Date().getTime()+'.jpg';
this.temp_image_name = new Date().getTime()+'.jpg';
let options: FileUploadOptions = {
fileKey: 'file',
fileName: this.temp_image_name,
headers: {}
.....
}
```

but it not working and file name return empty. have any idea on this issue. Thanks

Start with the FileUploadOptions usage shown in the issue and inspect how the plugin handles the fileName value during upload. No repository file, test, platform, or reproducible case is provided; done requires identifying the cause of the empty name and documenting or fixing a verified behavior.

Written by the indexing model from the issue text.