HDFS-15668. RBF: Fix RouterRPCMetrics annocation and document misplaced error. Contributed by Hongbing Wang.

hadoop-common-project/hadoop-common/src/site/markdown/Metrics.md

@@ -548,8 +548,8 @@ RouterRPCMetrics shows the statistics of the Router component in Router-based fe
 |:---- |:---- |
 | `ProcessingOp` | Number of operations the Router processed internally |
 | `ProxyOp` | Number of operations the Router proxied to a Namenode |
-| `ProxyOpFailureStandby` | Number of operations to fail to reach NN |
-| `ProxyOpFailureCommunicate` | Number of operations to hit a standby NN |
+| `ProxyOpFailureStandby` | Number of operations to hit a standby NN |
+| `ProxyOpFailureCommunicate` | Number of operations to fail to reach NN |
 | `ProxyOpNotImplemented` | Number of operations not implemented |
 | `RouterFailureStateStore` | Number of failed requests due to State Store unavailable |
 | `RouterFailureReadOnly` | Number of failed requests due to read only mount point |

hadoop-hdfs-project/hadoop-hdfs-rbf/src/main/java/org/apache/hadoop/hdfs/server/federation/metrics/FederationRPCMetrics.java

@@ -50,9 +50,9 @@ public class FederationRPCMetrics implements FederationRPCMBean {
   @Metric("Number of operations the Router proxied to a Namenode")
   private MutableCounterLong proxyOp;
 
-  @Metric("Number of operations to fail to reach NN")
-  private MutableCounterLong proxyOpFailureStandby;
   @Metric("Number of operations to hit a standby NN")
+  private MutableCounterLong proxyOpFailureStandby;
+  @Metric("Number of operations to fail to reach NN")
   private MutableCounterLong proxyOpFailureCommunicate;
   @Metric("Number of operations to hit a client overloaded Router")
   private MutableCounterLong proxyOpFailureClientOverloaded;