fixes in serialization

src/main/kotlin/com/github/insanusmokrassar/TelegramBotAPI/utils/StorageFile.kt

@@ -0,0 +1,20 @@
+package com.github.insanusmokrassar.TelegramBotAPI.utils
+
+import kotlinx.io.core.Input
+import kotlinx.io.streams.asInput
+import kotlinx.serialization.Serializable
+import kotlinx.serialization.Transient
+import java.io.File
+import java.nio.file.Files
+import java.util.*
+
+@Serializable
+data class StorageFile(
+    @Transient
+    private val file: File = throw IllegalStateException("Can't create object without file")
+) {
+    val contentType: String = Files.probeContentType(file.toPath())
+    val fileName: String = file.name
+    fun generateCustomName(): String = "${UUID.randomUUID()}.${file.extension}"
+    fun asInput(): Input = Files.newInputStream(file.toPath()).asInput()
+}