我们使用DataStaxJava驱动程序（v3.6.0）连接到cassandra（v3.11）。每当我们的infra团队关闭一个节点上的cassandra（一个节点接一个节点地修补操作系统）时，我们的查询就会一直正常运行。但是，我们在日志中确实看到了一些由datastax驱动程序中的空指针引起的错误：

Error parsing schema from Cassandra system tables: the schema in Cluster#getMetadata() will appear incomplete or stale

java.lang.NullPointerException: null
    at c.d.d.mapping.MappingManager$1.onTableChanged(MappingManager.java:160)
    at c.d.driver.core.Metadata.triggerOnTableChanged(Metadata.java:696)
    at c.d.driver.core.SchemaParser.updateTables(SchemaParser.java:484)
    at c.d.driver.core.SchemaParser.refresh(SchemaParser.java:130)
    at c.d.d.core.ControlConnection.refreshSchema(ControlConnection.java:408)
    at c.d.d.core.ControlConnection.refreshSchema(ControlConnection.java:354)
    at c.d.d.c.Cluster$Manager$SchemaRefreshRequestDeliveryCallback$1.runMayThrow(Cluster.java:2867)
    at c.d.d.c.ExceptionCatchingRunnable.run(ExceptionCatchingRunnable.java:32)
    at j.u.c.Executors$RunnableAdapter.call(Executors.java:511)
    at c.g.c.u.c.TrustedListenableFutureTask$TrustedFutureInterruptibleTask.runInterruptibly(TrustedListenableFutureTask.java:111)
    at c.g.c.u.c.InterruptibleTask.run(InterruptibleTask.java:58)
    at c.g.c.u.c.TrustedListenableFutureTask.run(TrustedListenableFutureTask.java:75)
    at j.u.c.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
    at j.u.c.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
    at i.n.u.c.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
    at java.lang.Thread.run(Thread.java:748)

有人觉得这个眼熟吗？虽然谷歌搜索这个问题，我找不到太多，所以我想知道我们是否做错了什么或这是一个已知的问题。。。