protected void onAcquire(PooledConnection conn, CurrentPassport passport) {
        passport.setOnChannel(conn.getChannel());
        removeIdleStateHandler(conn);

        conn.setInUse();
        LOG.debug("PooledConnection acquired: {}", 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