Add comment in getSubscriptionsInGroup about throwing IllegalStateException

Bug: 142250528
Test: build
Change-Id: I57b87755f6ddf962721e620f869ff48370e3f2d6
diff --git a/telephony/java/android/telephony/SubscriptionManager.java b/telephony/java/android/telephony/SubscriptionManager.java
index 126644d..c3a7985 100644
--- a/telephony/java/android/telephony/SubscriptionManager.java
+++ b/telephony/java/android/telephony/SubscriptionManager.java
@@ -2952,6 +2952,7 @@
      * permission or had carrier privilege permission on the subscription.
      * {@link TelephonyManager#hasCarrierPrivileges()}
      *
+     * @throws IllegalStateException if Telephony service is in bad state.
      * @throws SecurityException if the caller doesn't meet the requirements
      *             outlined above.
      *