diff --git a/hadoop-hdfs-project/hadoop-hdfs-rbf/src/main/java/org/apache/hadoop/hdfs/server/federation/router/RouterRpcServer.java b/hadoop-hdfs-project/hadoop-hdfs-rbf/src/main/java/org/apache/hadoop/hdfs/server/federation/router/RouterRpcServer.java
index 0b9d5eaa6897a..89d356cd4545e 100644
--- a/hadoop-hdfs-project/hadoop-hdfs-rbf/src/main/java/org/apache/hadoop/hdfs/server/federation/router/RouterRpcServer.java
+++ b/hadoop-hdfs-project/hadoop-hdfs-rbf/src/main/java/org/apache/hadoop/hdfs/server/federation/router/RouterRpcServer.java
@@ -1893,8 +1893,10 @@ public RouterClientProtocol getClientProtocolModule() {
 
   /**
    * Get RPC metrics info.
+   * May return null if `dfs.federation.router.metrics.enable` is false.
    * @return The instance of FederationRPCMetrics.
    */
+  @VisibleForTesting
   public FederationRPCMetrics getRPCMetrics() {
     return this.rpcMonitor.getRPCMetrics();
   }