@Override
      protected CompletableFuture<Set<ServerName>> fetchEndpoints() {
        return CompletableFuture.completedFuture(BOOTSTRAP_NODES);
      }
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