diff --git a/api/current.txt b/api/current.txt
index c8a7956075579..1227006dbe046 100644
--- a/api/current.txt
+++ b/api/current.txt
@@ -5943,7 +5943,7 @@ package android.app {
     method public boolean isImportantConversation();
     method public void setAllowBubbles(boolean);
     method public void setBypassDnd(boolean);
-    method public void setConversationId(@Nullable String, @Nullable String);
+    method public void setConversationId(@NonNull String, @NonNull String);
     method public void setDescription(String);
     method public void setGroup(String);
     method public void setImportance(int);
@@ -5956,7 +5956,6 @@ package android.app {
     method public boolean shouldShowLights();
     method public boolean shouldVibrate();
     method public void writeToParcel(android.os.Parcel, int);
-    field public static final String CONVERSATION_CHANNEL_ID_FORMAT = "%1$s : %2$s";
     field @NonNull public static final android.os.Parcelable.Creator<android.app.NotificationChannel> CREATOR;
     field public static final String DEFAULT_CHANNEL_ID = "miscellaneous";
   }
diff --git a/core/java/android/app/NotificationChannel.java b/core/java/android/app/NotificationChannel.java
index 7212be82d1a94..3f2ec4487668a 100644
--- a/core/java/android/app/NotificationChannel.java
+++ b/core/java/android/app/NotificationChannel.java
@@ -15,6 +15,7 @@
  */
 package android.app;
 
+import android.annotation.NonNull;
 import android.annotation.Nullable;
 import android.annotation.SystemApi;
 import android.annotation.TestApi;
@@ -63,6 +64,7 @@ public final class NotificationChannel implements Parcelable {
      * string takes two arguments, in this order: the
      * {@link #getId()} of the original notification channel, and the
      * {@link ShortcutInfo#getId() id} of the conversation.
+     * @hide
      */
     public static final String CONVERSATION_CHANNEL_ID_FORMAT = "%1$s : %2$s";
 
@@ -554,8 +556,8 @@ public final class NotificationChannel implements Parcelable {
     }
 
     /**
-     * Sets this channel as being person-centric. Different settings and functionality may be
-     * exposed for people-centric channels.
+     * Sets this channel as being converastion-centric. Different settings and functionality may be
+     * exposed for conversation-centric channels.
      *
      * @param parentChannelId The {@link #getId()} id} of the generic channel that notifications of
      *                        this type would be posted to in absence of a specific conversation id.
@@ -564,8 +566,8 @@ public final class NotificationChannel implements Parcelable {
      * @param conversationId The {@link ShortcutInfo#getId()} of the shortcut representing this
      *                       channel's conversation.
      */
-    public void setConversationId(@Nullable String parentChannelId,
-            @Nullable String conversationId) {
+    public void setConversationId(@NonNull String parentChannelId,
+            @NonNull String conversationId) {
         mParentId = parentChannelId;
         mConversationId = conversationId;
     }
diff --git a/core/java/android/app/NotificationManager.java b/core/java/android/app/NotificationManager.java
index 88edb05ba9683..cbbdf639d0369 100644
--- a/core/java/android/app/NotificationManager.java
+++ b/core/java/android/app/NotificationManager.java
@@ -1573,6 +1573,15 @@ public class NotificationManager {
                 PRIORITY_CATEGORY_CONVERSATIONS,
         };
 
+        /** @hide */
+        @IntDef(prefix = { "PRIORITY_SENDERS_" }, value = {
+                PRIORITY_SENDERS_ANY,
+                PRIORITY_SENDERS_CONTACTS,
+                PRIORITY_SENDERS_STARRED,
+        })
+        @Retention(RetentionPolicy.SOURCE)
+        public @interface PrioritySenders {}
+
         /** Any sender is prioritized. */
         public static final int PRIORITY_SENDERS_ANY = 0;
         /** Saved contacts are prioritized. */
@@ -1816,8 +1825,9 @@ public class NotificationManager {
          * @param suppressedVisualEffects which visual interruptions should be suppressed from
          *                                notifications that are filtered by DND.
          */
-        public Policy(int priorityCategories, int priorityCallSenders, int priorityMessageSenders,
-                int suppressedVisualEffects, int priorityConversationSenders) {
+        public Policy(int priorityCategories, @PrioritySenders int priorityCallSenders,
+                @PrioritySenders int priorityMessageSenders,
+                int suppressedVisualEffects, @ConversationSenders int priorityConversationSenders) {
             this(priorityCategories, priorityCallSenders, priorityMessageSenders,
                     suppressedVisualEffects, STATE_UNSET, priorityConversationSenders);
         }