export declare class EventSystemConnection {
    private sender;
    private listeners;
    private backlog;
    private maxBacklog;
    constructor(sender: HubEventSender);
    on<K extends HubEventNames>(event: K, action: HubEventListener<K>): {
        remove: () => void;
    };
    send<K extends HubEventNames>(eventName: K, content?: HubEventPayload<K> | null): Promise<void>;
    get unhandledEvents(): Record<string, string[]>;
    private retry;
}