class IterableEmbeddedManager: NSObject, IterableInternalEmbeddedManagerProtocol {
    ... 
    private var messages: [Int: [IterableEmbeddedMessage]] = [:]
   ...
    public func getMessages() -> [IterableEmbeddedMessage] { << not isolated
        return Array(messages.values.flatMap { $0 })
    }
...    
      private func retrieveEmbeddedMessages(completion: @escaping () -> Void) {
        apiClient.getEmbeddedMessages()
            .onCompletion(
                receiveValue: { embeddedMessagesPayload in
               ..
                    let processor = EmbeddedMessagingProcessor(currentMessages: self.messages, <<<< URLSession-Delegate Queue 
                                                               fetchedMessages: fetchedMessagesDict)
...
    private func setMessages(_ processor: EmbeddedMessagingProcessor) { << not isolated, called from several different threads
        messages = processor.processedMessagesList() 
        cleanUpTrackedMessageIds(messages)
    }
...
    
    public func reset() {
        let processor = EmbeddedMessagingProcessor(currentMessages: self.messages, fetchedMessages: [:])
        self.setMessages(processor)  << Message access on main thread