A helper object for adding file uploads to multipart forms via the [IMultipartFormSection] API.
This object is very similar to the [MultipartFormDataSection] object, but all constructors additionally accept (and require) a fileName parameter. If you omit the fileName parameter, this object will provide a default filename.
| contentType | Returns the value of the section's Content-Type header. |
| fileName | Returns a string denoting the desired filename of this section on the destination server. |
| sectionData | Returns the raw binary data contained in this section. Will not return null or a zero-length array. |
| sectionName | Returns the name of this section, if any. |
| MultipartFormFileSection | Contains a named file section based on the raw bytes from data, with a custom Content-Type and file name. |