Added the method setBusinessAccountUsername, allowing bots to change the username of a managed business account.

Author: mircoianese

library/src/main/java/com/pengrad/telegrambot/request/business/SetBusinessAccountUsername.kt

@@ -0,0 +1,24 @@
+package com.pengrad.telegrambot.request.business
+
+import com.pengrad.telegrambot.request.KBaseRequest
+import com.pengrad.telegrambot.response.BaseResponse
+import com.pengrad.telegrambot.utility.kotlin.optionalRequestParameter
+import com.pengrad.telegrambot.utility.kotlin.requestParameter
+
+@Suppress("unused")
+class SetBusinessAccountUsername private constructor(
+    businessConnectionId: String,
+    username: String?
+): KBaseRequest<SetBusinessAccountUsername, BaseResponse>(BaseResponse::class) {
+
+    constructor(businessConnectionId: String) : this(
+        businessConnectionId = businessConnectionId,
+        username = null
+    )
+
+    val businessConnectionId: String by requestParameter(businessConnectionId, customParameterName = "business_connection_id")
+
+    var username: String? by optionalRequestParameter(username, customParameterName = "username")
+    fun username(username: String) = applySelf { this.username = username }
+
+}