v2 `Jobs.UsersImports.Create` does not accept readers without name

[bendiknesbo]

Checklist

• I have looked into the README and have not found a suitable solution or answer.
• I have looked into the documentation and have not found a suitable solution or answer.
• I have searched the issues and have not found a suitable solution or answer.
• I have upgraded to the latest version of this SDK and the issue still persists.
• I have searched the Auth0 Community forums and have not found a suitable solution or answer.
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Description

I'm trying to run a Bulk User Import with 1 user, so I create the JSON in-memory and pass it to a bytes.NewReader. This is rejected by the Auth0 Management API with an error:

{"statusCode":400,"error":"Bad Request","message":"Payload validation error: 'Invalid multipart payload format'.","errorCode":"invalid_body"}

Expectation

I expect to be able to send any io.Reader to the mgmtClient.Jobs.UsersImports.Create, and it should start an import job.

Reproduction

The following two import-jobs are rejected.

	job := &management.CreateImportUsersRequestContent{
		ConnectionID:        "some connection ID",
		Upsert:              ptr(true),
		SendCompletionEmail: ptr(false),
		Users:               bytes.NewReader([]byte(`[{"user_id":"123"}]`)),
	}
	jobImportUserResp, err := ams.mgmtClient.Jobs.UsersImports.Create(ctx, job)

or

	job := &management.CreateImportUsersRequestContent{
		ConnectionID:        "some connection ID",
		Upsert:              ptr(true),
		SendCompletionEmail: ptr(false),
		Users:              strings.NewReader(`[{"user_id":"123"}]`),
	}
	jobImportUserResp, err := ams.mgmtClient.Jobs.UsersImports.Create(ctx, job)

---

If I read the content from a File by using os.Open, or if I wrap the reader in a struct that also implement the Name() string function, then it works as expected.

Auth0 Go SDK version

v2.2.0

[bendiknesbo]

It looks like if you use a pure bytes.Reader or strings.Reader or anything else that does not have a Name() string function, then the SDK will send the following header in the form-data: Content-Disposition: form-data; name="users"

But if we use a reader that have the Name() string function, it will send the following header: Content-Disposition: form-data; name="users"; filename="foobar".

The SDK should probably send a default filename for the users part, if one is not provided by the io.Reader.