diff --git a/core/java/android/app/usage/NetworkStatsManager.java b/core/java/android/app/usage/NetworkStatsManager.java
index fe99f85..8a6c85d 100644
--- a/core/java/android/app/usage/NetworkStatsManager.java
+++ b/core/java/android/app/usage/NetworkStatsManager.java
@@ -48,6 +48,7 @@
 import android.os.ServiceManager;
 import android.os.ServiceManager.ServiceNotFoundException;
 import android.telephony.TelephonyManager;
+import android.text.TextUtils;
 import android.util.DataUnit;
 import android.util.Log;
 
@@ -214,6 +215,10 @@
      *                     null} value when querying for the mobile network type to receive usage
      *                     for all mobile networks. For additional details see {@link
      *                     TelephonyManager#getSubscriberId()}.
+     *                     <p>Starting with API level 31, calling apps can provide a
+     *                     {@code subscriberId} with wifi network type to receive usage for
+     *                     wifi networks which is under the given subscription if applicable.
+     *                     Otherwise, pass {@code null} when querying all wifi networks.
      * @param startTime Start of period. Defined in terms of "Unix time", see
      *            {@link java.lang.System#currentTimeMillis}.
      * @param endTime End of period. Defined in terms of "Unix time", see
@@ -255,6 +260,10 @@
      *                     null} value when querying for the mobile network type to receive usage
      *                     for all mobile networks. For additional details see {@link
      *                     TelephonyManager#getSubscriberId()}.
+     *                     <p>Starting with API level 31, calling apps can provide a
+     *                     {@code subscriberId} with wifi network type to receive usage for
+     *                     wifi networks which is under the given subscription if applicable.
+     *                     Otherwise, pass {@code null} when querying all wifi networks.
      * @param startTime Start of period. Defined in terms of "Unix time", see
      *            {@link java.lang.System#currentTimeMillis}.
      * @param endTime End of period. Defined in terms of "Unix time", see
@@ -300,6 +309,10 @@
      *                     null} value when querying for the mobile network type to receive usage
      *                     for all mobile networks. For additional details see {@link
      *                     TelephonyManager#getSubscriberId()}.
+     *                     <p>Starting with API level 31, calling apps can provide a
+     *                     {@code subscriberId} with wifi network type to receive usage for
+     *                     wifi networks which is under the given subscription if applicable.
+     *                     Otherwise, pass {@code null} when querying all wifi networks.
      * @param startTime Start of period. Defined in terms of "Unix time", see
      *            {@link java.lang.System#currentTimeMillis}.
      * @param endTime End of period. Defined in terms of "Unix time", see
@@ -388,6 +401,10 @@
      *                     null} value when querying for the mobile network type to receive usage
      *                     for all mobile networks. For additional details see {@link
      *                     TelephonyManager#getSubscriberId()}.
+     *                     <p>Starting with API level 31, calling apps can provide a
+     *                     {@code subscriberId} with wifi network type to receive usage for
+     *                     wifi networks which is under the given subscription if applicable.
+     *                     Otherwise, pass {@code null} when querying all wifi networks.
      * @param startTime Start of period. Defined in terms of "Unix time", see
      *            {@link java.lang.System#currentTimeMillis}.
      * @param endTime End of period. Defined in terms of "Unix time", see
@@ -450,6 +467,10 @@
      *                     null} value when querying for the mobile network type to receive usage
      *                     for all mobile networks. For additional details see {@link
      *                     TelephonyManager#getSubscriberId()}.
+     *                     <p>Starting with API level 31, calling apps can provide a
+     *                     {@code subscriberId} with wifi network type to receive usage for
+     *                     wifi networks which is under the given subscription if applicable.
+     *                     Otherwise, pass {@code null} when querying all wifi networks.
      * @param startTime Start of period. Defined in terms of "Unix time", see
      *            {@link java.lang.System#currentTimeMillis}.
      * @param endTime End of period. Defined in terms of "Unix time", see
@@ -531,6 +552,10 @@
      *                     null} value when registering for the mobile network type to receive
      *                     notifications for all mobile networks. For additional details see {@link
      *                     TelephonyManager#getSubscriberId()}.
+     *                     <p>Starting with API level 31, calling apps can provide a
+     *                     {@code subscriberId} with wifi network type to receive usage for
+     *                     wifi networks which is under the given subscription if applicable.
+     *                     Otherwise, pass {@code null} when querying all wifi networks.
      * @param thresholdBytes Threshold in bytes to be notified on.
      * @param callback The {@link UsageCallback} that the system will call when data usage
      *            has exceeded the specified threshold.
@@ -644,7 +669,7 @@
                         : NetworkTemplate.buildTemplateMobileAll(subscriberId);
                 break;
             case ConnectivityManager.TYPE_WIFI:
-                template = subscriberId == null
+                template = TextUtils.isEmpty(subscriberId)
                         ? NetworkTemplate.buildTemplateWifiWildcard()
                         : NetworkTemplate.buildTemplateWifi(NetworkTemplate.WIFI_NETWORKID_ALL,
                                 subscriberId);