protected void createConnection(
            ChannelFuture cf, Promise<PooledConnection> callerPromise, CurrentPassport passport) {
        PooledConnection conn = pooledConnectionFactory.create(cf.channel());

        conn.incrementUsageCount();
        conn.startRequestTimer();
        conn.getChannel().read();
        onAcquire(conn, passport);
        callerPromise.setSuccess(conn);
    }
function to run when a connection is acquired before returning it to caller.
zuul-core/src/main/java/com/netflix/zuul/netty/connectionpool/PerServerConnectionPool.java