adding openGroupInvitation types in proto & class

libsession/src/main/java/org/session/libsession/messaging/messages/control/OpenGroupInvitation.kt

@@ -0,0 +1,51 @@
+package org.session.libsession.messaging.messages.control
+
+import org.session.libsignal.service.internal.push.SignalServiceProtos
+import org.session.libsignal.utilities.logging.Log
+
+class OpenGroupInvitation() : ControlMessage() {
+
+    var serverAddress: String? = null;
+    var channelId: Int? = 0;
+    var serverName: String? = null;
+
+    companion object {
+        const val TAG = "OpenGroupInvitation"
+
+        fun fromProto(proto: SignalServiceProtos.Content): OpenGroupInvitation? {
+            val openGroupInvitationProto = if (proto.hasOpenGroupInvitation()) proto.openGroupInvitation else return null
+            val serverAddress = openGroupInvitationProto.serverAddress
+            val channelId = openGroupInvitationProto.channelId
+            val serverName = openGroupInvitationProto.serverName
+            return OpenGroupInvitation(serverAddress, channelId, serverName)
+        }
+    }
+
+    constructor(serverAddress: String?, channelId: Int, serverName: String?): this() {
+        this.serverAddress = serverAddress
+        this.channelId = channelId
+        this.serverName = serverName
+    }
+
+    override fun isValid(): Boolean {
+        if (!super.isValid()) return false
+        //TODO determine what's required
+        return (serverAddress != null && channelId != null && serverName != null)
+    }
+
+    override fun toProto(): SignalServiceProtos.Content? {
+        val openGroupInvitationProto = SignalServiceProtos.OpenGroupInvitation.newBuilder()
+        openGroupInvitationProto.serverAddress = serverAddress
+        openGroupInvitationProto.channelId = channelId ?: 0
+        openGroupInvitationProto.serverName = serverName
+
+        val proto = SignalServiceProtos.Content.newBuilder()
+        return try {
+            proto.openGroupInvitation = openGroupInvitationProto.build()
+            proto.build()
+        } catch (e: Exception) {
+            Log.w(TAG, "Couldn't construct open group invitation proto from: $this")
+            null
+        }
+    }
+}

libsignal/protobuf/SignalService.proto

@@ -40,7 +40,8 @@ message Content {
   optional ReceiptMessage             receiptMessage             = 5;
   optional TypingMessage              typingMessage              = 6;
   optional ConfigurationMessage       configurationMessage       = 7;
-  optional DataExtractionNotification dataExtractionNotification = 82;
+  optional DataExtractionNotification dataExtractionNotification = 8;
+  optional OpenGroupInvitation        openGroupInvitation        = 9;
 }
 
 message KeyPair {
@@ -144,6 +145,12 @@ message DataMessage {
   optional string                    syncTarget                = 105;
 }
 
+message OpenGroupInvitation {
+    optional string serverAddress = 1;
+    optional uint32 channelId = 2;
+    optional string serverName = 3;
+  }
+
 message ConfigurationMessage {
 
   message ClosedGroup {