@Test
  public void testSecondRoundSucceededHedge4() throws IOException {
    GOOD_RESP_INDEXS = Collections.singleton(6);
    try (AbstractRpcBasedConnectionRegistry registry = createRegistry(4)) {
      String clusterId = logIfError(registry.getClusterId());
      assertEquals(RESP.getClusterId(), clusterId);
      UTIL.waitFor(5000, () -> CALLED.get() == 8);
    }
  }
A dummy RpcChannel implementation that intercepts the GetClusterId() RPC calls and injects
errors. All other RPCs are ignored.
hbase-client/src/test/java/org/apache/hadoop/hbase/client/TestRpcBasedRegistryHedgedReads.java