@Test
  public void testRetryOutOfOrderScannerNextException() throws IOException {
    expectRetryOutOfOrderScannerNext(this::getScanner);
  }
verify that we don't miss any data when encountering an OutOfOrderScannerNextException.
Typically, the only way to naturally trigger this is if a client-side timeout causes an
erroneous next() call. This is relatively hard to do these days because the server attempts to
always return before the timeout. In this test we force the server to throw this exception, so
that we can test the retry logic appropriately.
hbase-server/src/test/java/org/apache/hadoop/hbase/client/TestClientScannerTimeouts.java