uploadByStringId

@Multipart
@POST(value = "/api/ij-plugins/upload")
abstract override fun uploadByStringId(@Part(value = "xmlId") pluginXmlId: RequestBody, @Part(value = "channel") channel: RequestBody?, @Part(value = "notes") notes: RequestBody?, @Part(value = "isHidden") isHidden: Boolean, @Part file: MultipartBody.Part): Call<PluginUpdateBean>