toFormData should (optionally?) support array serialization (w/o [] suffix)

[plehnen]

Is your feature request related to a problem? Please describe.

While trying to migrate to the new FormData autogeneration (by using postForm or setting Content-Type to multipart) I realized arrays won't work anymore. An 'arr' proprety with two entries will be converted to name="arr.0" and name="arr.1" in the payload.
I saw in the source-code that once the name has a suffix like '[]' it will post it as such. But our springboot backend wants the key to be 'arr' (not 'arr[]') and our client-side typescript interface has a key named 'arr' and not 'arr[]' either.

Describe the solution you'd like

Plain arrays should also be send automatically, without the need to put '[]' to its name. If that's a breaking change, make it optional via options.

Describe alternatives you've considered

Springboot can't parse the default 'arr.0', 'arr.1' format. And adding '[]' to the type, the client-side object and the desired property in the backend is not an ideal solution.

In typescript properties of types/interfaces usually don't have a '[]' suffix. But the whole point of migrating to this new feature is to have type-safe services with a typed payload instead of just any 'FormData' object.

Additional context

[startjava]

#6266
@plehnen

same question , same spring boot envirment

[startjava]

@DigitalBrainJS
#4704
The contents of this URL still do not solve the problem of receiving array parameters in the springboot environment. In springboot, the foreground URL cannot have [] and., but the URL does not completely disable [] and. option