diff --git a/framework/src/android/net/LocalNetworkConfig.java b/framework/src/android/net/LocalNetworkConfig.java
index e1b33e8..17b1064 100644
--- a/framework/src/android/net/LocalNetworkConfig.java
+++ b/framework/src/android/net/LocalNetworkConfig.java
@@ -62,11 +62,19 @@
         return mUpstreamSelector;
     }
 
-    public @NonNull MulticastRoutingConfig getUpstreamMulticastRoutingConfig() {
+    /**
+     * Get the upstream multicast routing config
+     */
+    @NonNull
+    public MulticastRoutingConfig getUpstreamMulticastRoutingConfig() {
         return mUpstreamMulticastRoutingConfig;
     }
 
-    public @NonNull MulticastRoutingConfig getDownstreamMulticastRoutingConfig() {
+    /**
+     * Get the downstream multicast routing config
+     */
+    @NonNull
+    public MulticastRoutingConfig getDownstreamMulticastRoutingConfig() {
         return mDownstreamMulticastRoutingConfig;
     }
 
@@ -109,13 +117,13 @@
 
     public static final class Builder {
         @Nullable
-        NetworkRequest mUpstreamSelector;
+        private NetworkRequest mUpstreamSelector;
 
         @Nullable
-        MulticastRoutingConfig mUpstreamMulticastRoutingConfig;
+        private MulticastRoutingConfig mUpstreamMulticastRoutingConfig;
 
         @Nullable
-        MulticastRoutingConfig mDownstreamMulticastRoutingConfig;
+        private MulticastRoutingConfig mDownstreamMulticastRoutingConfig;
 
         /**
          * Create a Builder
diff --git a/framework/src/android/net/MulticastRoutingConfig.java b/framework/src/android/net/MulticastRoutingConfig.java
index 6f4ab11..1f4071c 100644
--- a/framework/src/android/net/MulticastRoutingConfig.java
+++ b/framework/src/android/net/MulticastRoutingConfig.java
@@ -38,8 +38,8 @@
  * Internal usage to Connectivity
  * @hide
  */
-// TODO : @SystemApi
-public class MulticastRoutingConfig implements Parcelable {
+// @SystemApi(client = MODULE_LIBRARIES)
+public final class MulticastRoutingConfig implements Parcelable {
     private static final String TAG = MulticastRoutingConfig.class.getSimpleName();
 
     /** Do not forward any multicast packets. */
@@ -55,6 +55,7 @@
      */
     public static final int FORWARD_WITH_MIN_SCOPE = 2;
 
+    /** @hide */
     @Retention(RetentionPolicy.SOURCE)
     @IntDef(prefix = { "FORWARD_" }, value = {
             FORWARD_NONE,
@@ -68,6 +69,7 @@
      */
     public static final int MULTICAST_SCOPE_NONE = -1;
 
+    /** @hide */
     public static final MulticastRoutingConfig CONFIG_FORWARD_NONE =
             new MulticastRoutingConfig(FORWARD_NONE, MULTICAST_SCOPE_NONE, null);
 
@@ -102,7 +104,7 @@
      * Returns the minimal group address scope that is allowed for forwarding.
      * If the forwarding mode is not FORWARD_WITH_MIN_SCOPE, will be MULTICAST_SCOPE_NONE.
      */
-    public int getMinScope() {
+    public int getMinimumScope() {
         return mMinScope;
     }
 
@@ -111,7 +113,7 @@
      * The list will be empty if the forwarding mode is not FORWARD_SELECTED.
      */
     @NonNull
-    public Set<Inet6Address> getMulticastListeningAddresses() {
+    public Set<Inet6Address> getListeningAddresses() {
         return mListeningAddresses;
     }
 
@@ -133,7 +135,7 @@
     }
 
     @Override
-    public void writeToParcel(Parcel dest, int flags) {
+    public void writeToParcel(@NonNull Parcel dest, int flags) {
         dest.writeInt(mForwardingMode);
         dest.writeInt(mMinScope);
         dest.writeInt(mListeningAddresses.size());
@@ -147,9 +149,10 @@
         return 0;
     }
 
+    @NonNull
     public static final Creator<MulticastRoutingConfig> CREATOR = new Creator<>() {
         @Override
-        public MulticastRoutingConfig createFromParcel(Parcel in) {
+        public MulticastRoutingConfig createFromParcel(@NonNull Parcel in) {
             return new MulticastRoutingConfig(in);
         }
 
@@ -177,43 +180,58 @@
         }
     }
 
-    public static class Builder {
+    public static final class Builder {
         @MulticastForwardingMode
         private final int mForwardingMode;
         private int mMinScope;
         private final ArraySet<Inet6Address> mListeningAddresses;
 
-        private Builder(@MulticastForwardingMode final int mode, int scope) {
+        // The two constructors with runtime checks for the mode and scope are arguably
+        // less convenient than three static factory methods, but API guidelines mandates
+        // that Builders are built with a constructor and not factory methods.
+        /**
+         * Create a new builder for forwarding mode FORWARD_NONE or FORWARD_SELECTED.
+         *
+         * <p>On a Builder for FORWARD_NONE, no properties can be set.
+         * <p>On a Builder for FORWARD_SELECTED, listening addresses can be added and removed
+         * but the minimum scope can't be set.
+         *
+         * @param mode {@link #FORWARD_NONE} or {@link #FORWARD_SELECTED}. Any other
+         *             value will result in IllegalArgumentException.
+         * @see #Builder(int, int)
+         */
+        public Builder(@MulticastForwardingMode final int mode) {
+            if (FORWARD_NONE != mode && FORWARD_SELECTED != mode) {
+                if (FORWARD_WITH_MIN_SCOPE == mode) {
+                    throw new IllegalArgumentException("FORWARD_WITH_MIN_SCOPE requires "
+                            + "passing the scope as a second argument");
+                } else {
+                    throw new IllegalArgumentException("Unknown forwarding mode : " + mode);
+                }
+            }
             mForwardingMode = mode;
-            mMinScope = scope;
+            mMinScope = MULTICAST_SCOPE_NONE;
             mListeningAddresses = new ArraySet<>();
         }
 
         /**
-         * Create a builder that forwards nothing.
-         * No properties can be set on such a builder.
-         */
-        public static Builder newBuilderForwardingNone() {
-            return new Builder(FORWARD_NONE, MULTICAST_SCOPE_NONE);
-        }
-
-        /**
-         * Create a builder that forwards packets above a certain scope
+         * Create a new builder for forwarding mode FORWARD_WITH_MIN_SCOPE.
          *
-         * The scope can be changed on this builder, but not the listening addresses.
-         * @param scope the initial scope
-         */
-        public static Builder newBuilderWithMinScope(final int scope) {
-            return new Builder(FORWARD_WITH_MIN_SCOPE, scope);
-        }
-
-        /**
-         * Create a builder that forwards a specified list of listening addresses.
+         * <p>On this Builder the scope can be set with {@link #setMinimumScope}, but
+         * listening addresses can't be added or removed.
          *
-         * Addresses can be added and removed from this builder, but the scope can't be set.
+         * @param mode Must be {@link #FORWARD_WITH_MIN_SCOPE}.
+         * @param scope the minimum scope for this multicast routing config.
+         * @see Builder#Builder(int)
          */
-        public static Builder newBuilderWithListeningAddresses() {
-            return new Builder(FORWARD_SELECTED, MULTICAST_SCOPE_NONE);
+        public Builder(@MulticastForwardingMode final int mode, int scope) {
+            if (FORWARD_WITH_MIN_SCOPE != mode) {
+                throw new IllegalArgumentException("Forwarding with a min scope must "
+                        + "use forward mode FORWARD_WITH_MIN_SCOPE");
+            }
+            mForwardingMode = mode;
+            mMinScope = scope;
+            mListeningAddresses = new ArraySet<>();
         }
 
         /**
@@ -221,6 +239,7 @@
          * This is only meaningful (indeed, allowed) for configs in FORWARD_WITH_MIN_SCOPE mode.
          * @return this builder
          */
+        @NonNull
         public Builder setMinimumScope(final int scope) {
             if (FORWARD_WITH_MIN_SCOPE != mForwardingMode) {
                 throw new IllegalArgumentException("Can't set the scope on a builder in mode "
@@ -237,6 +256,7 @@
          * If this address was already added, this is a no-op.
          * @return this builder
          */
+        @NonNull
         public Builder addListeningAddress(@NonNull final Inet6Address address) {
             if (FORWARD_SELECTED != mForwardingMode) {
                 throw new IllegalArgumentException("Can't add an address on a builder in mode "
@@ -254,7 +274,8 @@
          * If this address was not added, or was already removed, this is a no-op.
          * @return this builder
          */
-        public Builder removeListeningAddress(@NonNull final Inet6Address address) {
+        @NonNull
+        public Builder clearListeningAddress(@NonNull final Inet6Address address) {
             if (FORWARD_SELECTED != mForwardingMode) {
                 throw new IllegalArgumentException("Can't remove an address on a builder in mode "
                         + modeToString(mForwardingMode));
@@ -266,6 +287,7 @@
         /**
          * Build the config.
          */
+        @NonNull
         public MulticastRoutingConfig build() {
             return new MulticastRoutingConfig(mForwardingMode, mMinScope, mListeningAddresses);
         }