Upload multipart file

> **Required capabilities:** `filesAcl:WRITE` Multipart file upload enables upload of files larger than 5000 MB, using a uniform API on all cloud environments for CDF. Each file part must be larger than 5 MiB, and smaller than 4000 MiB. The file part for the last uploadURL can be smaller than 5 MiB. Maximum 250 upload URLs can be requested. The supported maximum size for each file uploaded with the multi-part upload API is therefore 1000 GiB (1.073 TB / 0.976 TiB). The client should calculate the ideal number of parts depending on predetermined or estimated file size, between 1 and the maximum. Specify the number of parts in the `parts` URL query parameter. The `parts` parameter is required. The request creates metadata information for a new file, and returns in addition to the file `id`, also a `uploadId`, and a list of `uploadUrls` for uploading the file contents. To upload a file, send an HTTP PUT request to each of the uploadUrls, with the corresponding part of the file in the request body. You may use a 'Content-Length' header in the PUT request for each part, but this is not required. A failed part PUT upload can be retried. The client must ensure that the parts of the source file are stored in the correct order, using the order of the `uploadUrls` as specified in the response. This to avoid ending up with a corrupt final file. The parts can optionally be uploaded in parallel, preferably on a subset of parts at a time, for example maximum 3 concurrent PUT operations. Once all file parts have been uploaded, the client should call the 'files/completemultipartupload' endpoint, with the required file ID (as `id` or `externalId`) and `uploadId` fields in the request body. This will assemble the parts into one file. The file's `uploaded` flag will then eventually be set to `true`. A standard sequence of calls to upload a large file with multipart upload would be for example as follows: 1. POST files/initmultipartupload?parts=8, to start a multipart upload session with 8 parts. Expect a 201 CREATED response code, and a response body with information to be used in the part uploads and completemultipartupload requests. 2. PUT `uploadUrl`, for each of the `uploadUrls` in the response from files/initmultipartupload. Expect a 200 OK or 201 CREATED response for each PUT request. 3. POST files/completemultipartupload, with request body '{ "id":123456789, "uploadId":"ABCD4321EFGH" }'. This will assemble the file. Expect a 200 OK response. Consider verifying that the file is eventually marked as uploaded with a call to the getFileByInternalId endpoint. NOTE: The uploadUrls expires after one week. A file that does not have the file content parts uploaded and completed within one week will be automatically deleted. ### Request throttling Please note that this endpoint is subject to the new throttling policy, which imposes limits on both request rate and concurrency. For more details, please refer to the [Files resource documentation](../../).