src/main/java/com/alipay/remoting/DefaultConnectionManager.java
@Override
    public Connection getAndCreateIfAbsent(Url url) throws InterruptedException, RemotingException {
        // get and create a connection pool with initialized connections.
        ConnectionPool pool = this.getConnectionPoolAndCreateIfAbsent(url.getUniqueKey(),
            new ConnectionPoolCall(url));
        if (null != pool) {
            return pool.get();
        } else {
            logger.error("[NOTIFYME] bug detected! pool here must not be null!");
            return null;
        }
    }
@Override
    public Connection getAndCreateIfAbsent(Url url) throws InterruptedException, RemotingException {
        // get and create a connection pool with initialized connections.
        ConnectionPool pool = this.getConnectionPoolAndCreateIfAbsent(url.getUniqueKey(),
            new ConnectionPoolCall(url));
        if (null != pool) {
            return pool.get();
        } else {
            logger.error("[NOTIFYME] bug detected! pool here must not be null!");
            return null;
        }
    }
If no task cached, create one and initialize the connections.

@see ConnectionManager#getAndCreateIfAbsent(Url)