diff --git a/service/mdns/com/android/server/connectivity/mdns/EnqueueMdnsQueryCallable.java b/service/mdns/com/android/server/connectivity/mdns/EnqueueMdnsQueryCallable.java
index f366363..f7871f3 100644
--- a/service/mdns/com/android/server/connectivity/mdns/EnqueueMdnsQueryCallable.java
+++ b/service/mdns/com/android/server/connectivity/mdns/EnqueueMdnsQueryCallable.java
@@ -17,6 +17,7 @@
 package com.android.server.connectivity.mdns;
 
 import android.annotation.NonNull;
+import android.annotation.Nullable;
 import android.text.TextUtils;
 import android.util.Pair;
 
@@ -38,8 +39,6 @@
  * and the list of the subtypes in the query as a {@link Pair}. If a query is failed to build, or if
  * it can not be enqueued, then call to {@link #call()} returns {@code null}.
  */
-// TODO(b/242631897): Resolve nullness suppression.
-@SuppressWarnings("nullness")
 public class EnqueueMdnsQueryCallable implements Callable<Pair<Integer, List<String>>> {
 
     private static final String TAG = "MdnsQueryCallable";
@@ -81,7 +80,10 @@
         this.transactionId = transactionId;
     }
 
+    // Incompatible return type for override of Callable#call().
+    @SuppressWarnings("nullness:override.return.invalid")
     @Override
+    @Nullable
     public Pair<Integer, List<String>> call() {
         try {
             MdnsSocketClient requestSender = weakRequestSender.get();
diff --git a/service/mdns/com/android/server/connectivity/mdns/MdnsConstants.java b/service/mdns/com/android/server/connectivity/mdns/MdnsConstants.java
index 0b2066a..396be5f 100644
--- a/service/mdns/com/android/server/connectivity/mdns/MdnsConstants.java
+++ b/service/mdns/com/android/server/connectivity/mdns/MdnsConstants.java
@@ -16,19 +16,15 @@
 
 package com.android.server.connectivity.mdns;
 
-import android.annotation.TargetApi;
-import android.os.Build;
+import static java.nio.charset.StandardCharsets.UTF_8;
 
 import com.android.internal.annotations.VisibleForTesting;
 
 import java.net.InetAddress;
 import java.net.UnknownHostException;
 import java.nio.charset.Charset;
-import java.nio.charset.StandardCharsets;
 
 /** mDNS-related constants. */
-// TODO(b/242631897): Resolve nullness suppression.
-@SuppressWarnings("nullness")
 @VisibleForTesting
 public final class MdnsConstants {
     public static final int MDNS_PORT = 5353;
@@ -48,7 +44,6 @@
     private static final String MDNS_IPV4_HOST_ADDRESS = "224.0.0.251";
     private static final String MDNS_IPV6_HOST_ADDRESS = "FF02::FB";
     private static InetAddress mdnsAddress;
-    private static Charset utf8Charset;
     private MdnsConstants() {
     }
 
@@ -79,16 +74,6 @@
     }
 
     public static Charset getUtf8Charset() {
-        synchronized (MdnsConstants.class) {
-            if (utf8Charset == null) {
-                utf8Charset = getUtf8CharsetOnKitKat();
-            }
-            return utf8Charset;
-        }
-    }
-
-    @TargetApi(Build.VERSION_CODES.KITKAT)
-    private static Charset getUtf8CharsetOnKitKat() {
-        return StandardCharsets.UTF_8;
+        return UTF_8;
     }
 }
\ No newline at end of file
diff --git a/service/mdns/com/android/server/connectivity/mdns/MdnsInetAddressRecord.java b/service/mdns/com/android/server/connectivity/mdns/MdnsInetAddressRecord.java
index bd47414..47ac20e 100644
--- a/service/mdns/com/android/server/connectivity/mdns/MdnsInetAddressRecord.java
+++ b/service/mdns/com/android/server/connectivity/mdns/MdnsInetAddressRecord.java
@@ -16,6 +16,8 @@
 
 package com.android.server.connectivity.mdns;
 
+import android.annotation.Nullable;
+
 import com.android.internal.annotations.VisibleForTesting;
 
 import java.io.IOException;
@@ -27,12 +29,10 @@
 import java.util.Objects;
 
 /** An mDNS "AAAA" or "A" record, which holds an IPv6 or IPv4 address. */
-// TODO(b/242631897): Resolve nullness suppression.
-@SuppressWarnings("nullness")
 @VisibleForTesting
 public class MdnsInetAddressRecord extends MdnsRecord {
-    private Inet6Address inet6Address;
-    private Inet4Address inet4Address;
+    @Nullable private Inet6Address inet6Address;
+    @Nullable private Inet4Address inet4Address;
 
     /**
      * Constructs the {@link MdnsRecord}
@@ -47,11 +47,13 @@
     }
 
     /** Returns the IPv6 address. */
+    @Nullable
     public Inet6Address getInet6Address() {
         return inet6Address;
     }
 
     /** Returns the IPv4 address. */
+    @Nullable
     public Inet4Address getInet4Address() {
         return inet4Address;
     }
@@ -113,7 +115,7 @@
     }
 
     @Override
-    public boolean equals(Object other) {
+    public boolean equals(@Nullable Object other) {
         if (this == other) {
             return true;
         }
diff --git a/service/mdns/com/android/server/connectivity/mdns/MdnsPointerRecord.java b/service/mdns/com/android/server/connectivity/mdns/MdnsPointerRecord.java
index 0166815..9641a40 100644
--- a/service/mdns/com/android/server/connectivity/mdns/MdnsPointerRecord.java
+++ b/service/mdns/com/android/server/connectivity/mdns/MdnsPointerRecord.java
@@ -16,14 +16,14 @@
 
 package com.android.server.connectivity.mdns;
 
+import android.annotation.Nullable;
+
 import com.android.internal.annotations.VisibleForTesting;
 
 import java.io.IOException;
 import java.util.Arrays;
 
 /** An mDNS "PTR" record, which holds a name (the "pointer"). */
-// TODO(b/242631897): Resolve nullness suppression.
-@SuppressWarnings("nullness")
 @VisibleForTesting
 public class MdnsPointerRecord extends MdnsRecord {
     private String[] pointer;
@@ -66,7 +66,7 @@
     }
 
     @Override
-    public boolean equals(Object other) {
+    public boolean equals(@Nullable Object other) {
         if (this == other) {
             return true;
         }
diff --git a/service/mdns/com/android/server/connectivity/mdns/MdnsRecord.java b/service/mdns/com/android/server/connectivity/mdns/MdnsRecord.java
index 24fb09e..35f6da1 100644
--- a/service/mdns/com/android/server/connectivity/mdns/MdnsRecord.java
+++ b/service/mdns/com/android/server/connectivity/mdns/MdnsRecord.java
@@ -16,6 +16,10 @@
 
 package com.android.server.connectivity.mdns;
 
+import static java.util.concurrent.TimeUnit.MILLISECONDS;
+import static java.util.concurrent.TimeUnit.SECONDS;
+
+import android.annotation.Nullable;
 import android.os.SystemClock;
 import android.text.TextUtils;
 
@@ -24,14 +28,11 @@
 import java.io.IOException;
 import java.util.Arrays;
 import java.util.Objects;
-import java.util.concurrent.TimeUnit;
 
 /**
  * Abstract base class for mDNS records. Stores the header fields and provides methods for reading
  * the record from and writing it to a packet.
  */
-// TODO(b/242631897): Resolve nullness suppression.
-@SuppressWarnings("nullness")
 public abstract class MdnsRecord {
     public static final int TYPE_A = 0x0001;
     public static final int TYPE_AAAA = 0x001C;
@@ -59,11 +60,14 @@
      * @param reader The reader to read the record from.
      * @throws IOException If an error occurs while reading the packet.
      */
+    // call to readData(com.android.server.connectivity.mdns.MdnsPacketReader) not allowed on given
+    // receiver.
+    @SuppressWarnings("nullness:method.invocation.invalid")
     protected MdnsRecord(String[] name, int type, MdnsPacketReader reader) throws IOException {
         this.name = name;
         this.type = type;
         cls = reader.readUInt16();
-        ttlMillis = TimeUnit.SECONDS.toMillis(reader.readUInt32());
+        ttlMillis = SECONDS.toMillis(reader.readUInt32());
         int dataLength = reader.readUInt16();
 
         receiptTimeMillis = SystemClock.elapsedRealtime();
@@ -157,7 +161,7 @@
         writer.writeUInt16(type);
         writer.writeUInt16(cls);
 
-        writer.writeUInt32(TimeUnit.MILLISECONDS.toSeconds(getRemainingTTL(now)));
+        writer.writeUInt32(MILLISECONDS.toSeconds(getRemainingTTL(now)));
 
         int dataLengthPos = writer.getWritePosition();
         writer.writeUInt16(0); // data length
@@ -194,7 +198,7 @@
     }
 
     @Override
-    public boolean equals(Object other) {
+    public boolean equals(@Nullable Object other) {
         if (!(other instanceof MdnsRecord)) {
             return false;
         }
@@ -231,7 +235,7 @@
         }
 
         @Override
-        public boolean equals(Object other) {
+        public boolean equals(@Nullable Object other) {
             if (this == other) {
                 return true;
             }
diff --git a/service/mdns/com/android/server/connectivity/mdns/MdnsResponse.java b/service/mdns/com/android/server/connectivity/mdns/MdnsResponse.java
index c94e3c6..623168c 100644
--- a/service/mdns/com/android/server/connectivity/mdns/MdnsResponse.java
+++ b/service/mdns/com/android/server/connectivity/mdns/MdnsResponse.java
@@ -16,6 +16,8 @@
 
 package com.android.server.connectivity.mdns;
 
+import android.annotation.Nullable;
+
 import com.android.internal.annotations.VisibleForTesting;
 
 import java.io.IOException;
@@ -25,8 +27,6 @@
 import java.util.List;
 
 /** An mDNS response. */
-// TODO(b/242631897): Resolve nullness suppression.
-@SuppressWarnings("nullness")
 public class MdnsResponse {
     private final List<MdnsRecord> records;
     private final List<MdnsPointerRecord> pointerRecords;
@@ -78,7 +78,7 @@
     }
 
     @VisibleForTesting
-    /* package */ synchronized void clearPointerRecords() {
+    synchronized void clearPointerRecords() {
         pointerRecords.clear();
     }
 
@@ -91,15 +91,16 @@
         return false;
     }
 
+    @Nullable
     public synchronized List<String> getSubtypes() {
         List<String> subtypes = null;
-
         for (MdnsPointerRecord pointerRecord : pointerRecords) {
-            if (pointerRecord.hasSubtype()) {
+            String pointerRecordSubtype = pointerRecord.getSubtype();
+            if (pointerRecordSubtype != null) {
                 if (subtypes == null) {
                     subtypes = new LinkedList<>();
                 }
-                subtypes.add(pointerRecord.getSubtype());
+                subtypes.add(pointerRecordSubtype);
             }
         }
 
@@ -166,7 +167,8 @@
     }
 
     /** Sets the IPv4 address record. */
-    public synchronized boolean setInet4AddressRecord(MdnsInetAddressRecord newInet4AddressRecord) {
+    public synchronized boolean setInet4AddressRecord(
+            @Nullable MdnsInetAddressRecord newInet4AddressRecord) {
         if (recordsAreSame(this.inet4AddressRecord, newInet4AddressRecord)) {
             return false;
         }
@@ -190,7 +192,8 @@
     }
 
     /** Sets the IPv6 address record. */
-    public synchronized boolean setInet6AddressRecord(MdnsInetAddressRecord newInet6AddressRecord) {
+    public synchronized boolean setInet6AddressRecord(
+            @Nullable MdnsInetAddressRecord newInet6AddressRecord) {
         if (recordsAreSame(this.inet6AddressRecord, newInet6AddressRecord)) {
             return false;
         }
diff --git a/service/mdns/com/android/server/connectivity/mdns/MdnsResponseDecoder.java b/service/mdns/com/android/server/connectivity/mdns/MdnsResponseDecoder.java
index e73de55..861acbb 100644
--- a/service/mdns/com/android/server/connectivity/mdns/MdnsResponseDecoder.java
+++ b/service/mdns/com/android/server/connectivity/mdns/MdnsResponseDecoder.java
@@ -31,8 +31,6 @@
 import java.util.List;
 
 /** A class that decodes mDNS responses from UDP packets. */
-// TODO(b/242631897): Resolve nullness suppression.
-@SuppressWarnings("nullness")
 public class MdnsResponseDecoder {
 
     public static final int SUCCESS = 0;
@@ -40,7 +38,7 @@
     private static final MdnsLogger LOGGER = new MdnsLogger(TAG);
     private final boolean allowMultipleSrvRecordsPerHost =
             MdnsConfigs.allowMultipleSrvRecordsPerHost();
-    private final String[] serviceType;
+    @Nullable private final String[] serviceType;
     private final Clock clock;
 
     /** Constructs a new decoder that will extract responses for the given service type. */
diff --git a/service/mdns/com/android/server/connectivity/mdns/MdnsServiceInfo.java b/service/mdns/com/android/server/connectivity/mdns/MdnsServiceInfo.java
index 7d645e3..f1b2def 100644
--- a/service/mdns/com/android/server/connectivity/mdns/MdnsServiceInfo.java
+++ b/service/mdns/com/android/server/connectivity/mdns/MdnsServiceInfo.java
@@ -72,7 +72,9 @@
     private final List<String> subtypes;
     private final String[] hostName;
     private final int port;
+    @Nullable
     private final String ipv4Address;
+    @Nullable
     private final String ipv6Address;
     final List<String> textStrings;
     @Nullable
@@ -85,12 +87,12 @@
     public MdnsServiceInfo(
             String serviceInstanceName,
             String[] serviceType,
-            List<String> subtypes,
+            @Nullable List<String> subtypes,
             String[] hostName,
             int port,
-            String ipv4Address,
-            String ipv6Address,
-            List<String> textStrings) {
+            @Nullable String ipv4Address,
+            @Nullable String ipv6Address,
+            @Nullable List<String> textStrings) {
         this(
                 serviceInstanceName,
                 serviceType,
@@ -111,9 +113,9 @@
             List<String> subtypes,
             String[] hostName,
             int port,
-            String ipv4Address,
-            String ipv6Address,
-            List<String> textStrings,
+            @Nullable String ipv4Address,
+            @Nullable String ipv6Address,
+            @Nullable List<String> textStrings,
             @Nullable List<TextEntry> textEntries) {
         this(
                 serviceInstanceName,
@@ -136,12 +138,12 @@
     public MdnsServiceInfo(
             String serviceInstanceName,
             String[] serviceType,
-            List<String> subtypes,
+            @Nullable List<String> subtypes,
             String[] hostName,
             int port,
-            String ipv4Address,
-            String ipv6Address,
-            List<String> textStrings,
+            @Nullable String ipv4Address,
+            @Nullable String ipv6Address,
+            @Nullable List<String> textStrings,
             @Nullable List<TextEntry> textEntries,
             int interfaceIndex) {
         this.serviceInstanceName = serviceInstanceName;
@@ -191,45 +193,44 @@
         return Collections.unmodifiableList(list);
     }
 
-    /** @return the name of this service instance. */
+    /** Returns the name of this service instance. */
     public String getServiceInstanceName() {
         return serviceInstanceName;
     }
 
-    /** @return the type of this service instance. */
+    /** Returns the type of this service instance. */
     public String[] getServiceType() {
         return serviceType;
     }
 
-    /** @return the list of subtypes supported by this service instance. */
+    /** Returns the list of subtypes supported by this service instance. */
     public List<String> getSubtypes() {
         return new ArrayList<>(subtypes);
     }
 
-    /**
-     * @return {@code true} if this service instance supports any subtypes.
-     * @return {@code false} if this service instance does not support any subtypes.
-     */
+    /** Returns {@code true} if this service instance supports any subtypes. */
     public boolean hasSubtypes() {
         return !subtypes.isEmpty();
     }
 
-    /** @return the host name of this service instance. */
+    /** Returns the host name of this service instance. */
     public String[] getHostName() {
         return hostName;
     }
 
-    /** @return the port number of this service instance. */
+    /** Returns the port number of this service instance. */
     public int getPort() {
         return port;
     }
 
-    /** @return the IPV4 address of this service instance. */
+    /** Returns the IPV4 address of this service instance. */
+    @Nullable
     public String getIpv4Address() {
         return ipv4Address;
     }
 
-    /** @return the IPV6 address of this service instance. */
+    /** Returns the IPV6 address of this service instance. */
+    @Nullable
     public String getIpv6Address() {
         return ipv6Address;
     }
@@ -265,7 +266,7 @@
         return attributes.get(key.toLowerCase(Locale.ENGLISH));
     }
 
-    /** @return an immutable map of all attributes. */
+    /** Returns an immutable map of all attributes. */
     public Map<String, String> getAttributes() {
         Map<String, String> map = new HashMap<>(attributes.size());
         for (Map.Entry<String, byte[]> kv : attributes.entrySet()) {
diff --git a/service/mdns/com/android/server/connectivity/mdns/MdnsServiceRecord.java b/service/mdns/com/android/server/connectivity/mdns/MdnsServiceRecord.java
index 7f54d96..c52d25e 100644
--- a/service/mdns/com/android/server/connectivity/mdns/MdnsServiceRecord.java
+++ b/service/mdns/com/android/server/connectivity/mdns/MdnsServiceRecord.java
@@ -16,6 +16,8 @@
 
 package com.android.server.connectivity.mdns;
 
+import android.annotation.Nullable;
+
 import com.android.internal.annotations.VisibleForTesting;
 
 import java.io.IOException;
@@ -24,8 +26,6 @@
 import java.util.Objects;
 
 /** An mDNS "SRV" record, which contains service information. */
-// TODO(b/242631897): Resolve nullness suppression.
-@SuppressWarnings("nullness")
 @VisibleForTesting
 public class MdnsServiceRecord extends MdnsRecord {
     public static final int PROTO_NONE = 0;
@@ -131,7 +131,7 @@
     }
 
     @Override
-    public boolean equals(Object other) {
+    public boolean equals(@Nullable Object other) {
         if (this == other) {
             return true;
         }
diff --git a/service/mdns/com/android/server/connectivity/mdns/MdnsServiceTypeClient.java b/service/mdns/com/android/server/connectivity/mdns/MdnsServiceTypeClient.java
index be993e2..8ca71b9 100644
--- a/service/mdns/com/android/server/connectivity/mdns/MdnsServiceTypeClient.java
+++ b/service/mdns/com/android/server/connectivity/mdns/MdnsServiceTypeClient.java
@@ -29,6 +29,8 @@
 import com.android.internal.annotations.VisibleForTesting;
 import com.android.server.connectivity.mdns.util.MdnsLogger;
 
+import java.net.Inet4Address;
+import java.net.Inet6Address;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.HashMap;
@@ -43,8 +45,6 @@
  * Instance of this class sends and receives mDNS packets of a given service type and invoke
  * registered {@link MdnsServiceBrowserListener} instances.
  */
-// TODO(b/242631897): Resolve nullness suppression.
-@SuppressWarnings("nullness")
 public class MdnsServiceTypeClient {
 
     private static final int DEFAULT_MTU = 1500;
@@ -70,6 +70,7 @@
     private long currentSessionId = 0;
 
     @GuardedBy("lock")
+    @Nullable
     private Future<?> requestTaskFuture;
 
     /**
@@ -96,14 +97,25 @@
         String ipv4Address = null;
         String ipv6Address = null;
         if (response.hasInet4AddressRecord()) {
-            ipv4Address = response.getInet4AddressRecord().getInet4Address().getHostAddress();
+            Inet4Address inet4Address = response.getInet4AddressRecord().getInet4Address();
+            ipv4Address = (inet4Address == null) ? null : inet4Address.getHostAddress();
         }
         if (response.hasInet6AddressRecord()) {
-            ipv6Address = response.getInet6AddressRecord().getInet6Address().getHostAddress();
+            Inet6Address inet6Address = response.getInet6AddressRecord().getInet6Address();
+            ipv6Address = (inet6Address == null) ? null : inet6Address.getHostAddress();
+        }
+        if (ipv4Address == null && ipv6Address == null) {
+            throw new IllegalArgumentException(
+                    "Either ipv4Address or ipv6Address must be non-null");
+        }
+        String serviceInstanceName = response.getServiceInstanceName();
+        if (serviceInstanceName == null) {
+            throw new IllegalStateException(
+                    "mDNS response must have non-null service instance name");
         }
         // TODO: Throw an error message if response doesn't have Inet6 or Inet4 address.
         return new MdnsServiceInfo(
-                response.getServiceInstanceName(),
+                serviceInstanceName,
                 serviceTypeLabels,
                 response.getSubtypes(),
                 hostName,
@@ -128,8 +140,7 @@
             @NonNull MdnsSearchOptions searchOptions) {
         synchronized (lock) {
             this.searchOptions = searchOptions;
-            if (!listeners.contains(listener)) {
-                listeners.add(listener);
+            if (listeners.add(listener)) {
                 for (MdnsResponse existingResponse : instanceNameToResponse.values()) {
                     if (existingResponse.isComplete()) {
                         listener.onServiceFound(
@@ -212,7 +223,10 @@
         if (currentResponse == null) {
             newServiceFound = true;
             currentResponse = response;
-            instanceNameToResponse.put(response.getServiceInstanceName(), currentResponse);
+            String serviceInstanceName = response.getServiceInstanceName();
+            if (serviceInstanceName != null) {
+                instanceNameToResponse.put(serviceInstanceName, currentResponse);
+            }
         } else if (currentResponse.mergeRecordsFrom(response)) {
             existingServiceChanged = true;
         }
@@ -231,7 +245,10 @@
         }
     }
 
-    private void onGoodbyeReceived(@NonNull String serviceInstanceName) {
+    private void onGoodbyeReceived(@Nullable String serviceInstanceName) {
+        if (serviceInstanceName == null) {
+            return;
+        }
         instanceNameToResponse.remove(serviceInstanceName);
         for (MdnsServiceBrowserListener listener : listeners) {
             listener.onServiceRemoved(serviceInstanceName);
@@ -367,7 +384,7 @@
                                 config.expectUnicastResponse,
                                 config.transactionId)
                                 .call();
-            } catch (Exception e) {
+            } catch (RuntimeException e) {
                 LOGGER.e(String.format("Failed to run EnqueueMdnsQueryCallable for subtype: %s",
                         TextUtils.join(",", config.subtypes)), e);
                 result = null;
@@ -405,8 +422,11 @@
                                 == 0) {
                             iter.remove();
                             for (MdnsServiceBrowserListener listener : listeners) {
-                                listener.onServiceRemoved(
-                                        existingResponse.getServiceInstanceName());
+                                String serviceInstanceName =
+                                        existingResponse.getServiceInstanceName();
+                                if (serviceInstanceName != null) {
+                                    listener.onServiceRemoved(serviceInstanceName);
+                                }
                             }
                         }
                     }
diff --git a/service/mdns/com/android/server/connectivity/mdns/MdnsSocket.java b/service/mdns/com/android/server/connectivity/mdns/MdnsSocket.java
index 3442430..0a9b2fc 100644
--- a/service/mdns/com/android/server/connectivity/mdns/MdnsSocket.java
+++ b/service/mdns/com/android/server/connectivity/mdns/MdnsSocket.java
@@ -34,8 +34,6 @@
  *
  * @see MulticastSocket for javadoc of each public method.
  */
-// TODO(b/242631897): Resolve nullness suppression.
-@SuppressWarnings("nullness")
 public class MdnsSocket {
     private static final MdnsLogger LOGGER = new MdnsLogger("MdnsSocket");
 
@@ -44,16 +42,22 @@
             new InetSocketAddress(MdnsConstants.getMdnsIPv4Address(), MdnsConstants.MDNS_PORT);
     private static final InetSocketAddress MULTICAST_IPV6_ADDRESS =
             new InetSocketAddress(MdnsConstants.getMdnsIPv6Address(), MdnsConstants.MDNS_PORT);
-    private static boolean isOnIPv6OnlyNetwork = false;
     private final MulticastNetworkInterfaceProvider multicastNetworkInterfaceProvider;
     private final MulticastSocket multicastSocket;
+    private boolean isOnIPv6OnlyNetwork;
 
     public MdnsSocket(
             @NonNull MulticastNetworkInterfaceProvider multicastNetworkInterfaceProvider, int port)
             throws IOException {
+        this(multicastNetworkInterfaceProvider, new MulticastSocket(port));
+    }
+
+    @VisibleForTesting
+    MdnsSocket(@NonNull MulticastNetworkInterfaceProvider multicastNetworkInterfaceProvider,
+            MulticastSocket multicastSocket) throws IOException {
         this.multicastNetworkInterfaceProvider = multicastNetworkInterfaceProvider;
         this.multicastNetworkInterfaceProvider.startWatchingConnectivityChanges();
-        multicastSocket = createMulticastSocket(port);
+        this.multicastSocket = multicastSocket;
         // RFC Spec: https://tools.ietf.org/html/rfc6762
         // Time to live is set 255, which is similar to the jMDNS implementation.
         multicastSocket.setTimeToLive(255);
@@ -121,11 +125,6 @@
         }
     }
 
-    @VisibleForTesting
-    MulticastSocket createMulticastSocket(int port) throws IOException {
-        return new MulticastSocket(port);
-    }
-
     public boolean isOnIPv6OnlyNetwork() {
         return isOnIPv6OnlyNetwork;
     }
diff --git a/service/mdns/com/android/server/connectivity/mdns/MdnsSocketClient.java b/service/mdns/com/android/server/connectivity/mdns/MdnsSocketClient.java
index 6cbe3c7..758221a 100644
--- a/service/mdns/com/android/server/connectivity/mdns/MdnsSocketClient.java
+++ b/service/mdns/com/android/server/connectivity/mdns/MdnsSocketClient.java
@@ -46,8 +46,6 @@
  *
  * <p>See https://tools.ietf.org/html/rfc6763 (namely sections 4 and 5).
  */
-// TODO(b/242631897): Resolve nullness suppression.
-@SuppressWarnings("nullness")
 public class MdnsSocketClient {
 
     private static final String TAG = "MdnsClient";
@@ -71,7 +69,7 @@
     final Queue<DatagramPacket> unicastPacketQueue = new ArrayDeque<>();
     private final Context context;
     private final byte[] multicastReceiverBuffer = new byte[RECEIVER_BUFFER_SIZE];
-    private final byte[] unicastReceiverBuffer;
+    @Nullable private final byte[] unicastReceiverBuffer;
     private final MdnsResponseDecoder responseDecoder;
     private final MulticastLock multicastLock;
     private final boolean useSeparateSocketForUnicast =
@@ -94,20 +92,17 @@
     // If the phone is the bad state where it can't receive any multicast response.
     @VisibleForTesting
     AtomicBoolean cannotReceiveMulticastResponse = new AtomicBoolean(false);
-    @VisibleForTesting
-    volatile Thread sendThread;
-    @VisibleForTesting
-    Thread multicastReceiveThread;
-    @VisibleForTesting
-    Thread unicastReceiveThread;
+    @VisibleForTesting @Nullable volatile Thread sendThread;
+    @VisibleForTesting @Nullable Thread multicastReceiveThread;
+    @VisibleForTesting @Nullable Thread unicastReceiveThread;
     private volatile boolean shouldStopSocketLoop;
-    private Callback callback;
-    private MdnsSocket multicastSocket;
-    private MdnsSocket unicastSocket;
+    @Nullable private Callback callback;
+    @Nullable private MdnsSocket multicastSocket;
+    @Nullable private MdnsSocket unicastSocket;
     private int receivedPacketNumber = 0;
-    private Timer logMdnsPacketTimer;
+    @Nullable private Timer logMdnsPacketTimer;
     private AtomicInteger packetsCount;
-    private Timer checkMulticastResponseTimer;
+    @Nullable private Timer checkMulticastResponseTimer;
 
     public MdnsSocketClient(@NonNull Context context, @NonNull MulticastLock multicastLock) {
         this.context = context;
@@ -248,7 +243,12 @@
 
         if (useSeparateSocketForUnicast) {
             unicastReceiveThread =
-                    new Thread(() -> receiveThreadMain(unicastReceiverBuffer, unicastSocket));
+                    new Thread(
+                            () -> {
+                                if (unicastReceiverBuffer != null) {
+                                    receiveThreadMain(unicastReceiverBuffer, unicastSocket);
+                                }
+                            });
             unicastReceiveThread.setName("mdns-unicast-receive");
             unicastReceiveThread.start();
         }
@@ -327,11 +327,15 @@
                             unicastPacketsToSend.addAll(unicastPacketQueue);
                             unicastPacketQueue.clear();
                         }
+                        if (unicastSocket != null) {
+                            sendPackets(unicastPacketsToSend, unicastSocket);
+                        }
                     }
 
-                    // Send all the packets.
-                    sendPackets(multicastPacketsToSend, multicastSocket);
-                    sendPackets(unicastPacketsToSend, unicastSocket);
+                    // Send multicast packets.
+                    if (multicastSocket != null) {
+                        sendPackets(multicastPacketsToSend, multicastSocket);
+                    }
 
                     // Sleep ONLY if no more packets have been added to the queue, while packets
                     // were being sent.
@@ -351,7 +355,9 @@
         } finally {
             LOGGER.log("Send thread stopped.");
             try {
-                multicastSocket.leaveGroup();
+                if (multicastSocket != null) {
+                    multicastSocket.leaveGroup();
+                }
             } catch (Exception t) {
                 LOGGER.e("Failed to leave the group.", t);
             }
@@ -359,17 +365,19 @@
             // Close the socket first. This is the only way to interrupt a blocking receive.
             try {
                 // This is a race with the use of the file descriptor (b/27403984).
-                multicastSocket.close();
+                if (multicastSocket != null) {
+                    multicastSocket.close();
+                }
                 if (unicastSocket != null) {
                     unicastSocket.close();
                 }
-            } catch (Exception t) {
+            } catch (RuntimeException t) {
                 LOGGER.e("Failed to close the mdns socket.", t);
             }
         }
     }
 
-    private void receiveThreadMain(byte[] receiverBuffer, MdnsSocket socket) {
+    private void receiveThreadMain(byte[] receiverBuffer, @Nullable MdnsSocket socket) {
         DatagramPacket packet = new DatagramPacket(receiverBuffer, receiverBuffer.length);
 
         while (!shouldStopSocketLoop) {
@@ -500,7 +508,7 @@
     }
 
     public boolean isOnIPv6OnlyNetwork() {
-        return multicastSocket.isOnIPv6OnlyNetwork();
+        return multicastSocket != null && multicastSocket.isOnIPv6OnlyNetwork();
     }
 
     /** Callback for {@link MdnsSocketClient}. */
diff --git a/service/mdns/com/android/server/connectivity/mdns/MdnsTextRecord.java b/service/mdns/com/android/server/connectivity/mdns/MdnsTextRecord.java
index 73ecdfa..1e66589 100644
--- a/service/mdns/com/android/server/connectivity/mdns/MdnsTextRecord.java
+++ b/service/mdns/com/android/server/connectivity/mdns/MdnsTextRecord.java
@@ -16,6 +16,8 @@
 
 package com.android.server.connectivity.mdns;
 
+import android.annotation.Nullable;
+
 import com.android.internal.annotations.VisibleForTesting;
 import com.android.server.connectivity.mdns.MdnsServiceInfo.TextEntry;
 
@@ -26,8 +28,6 @@
 import java.util.Objects;
 
 /** An mDNS "TXT" record, which contains a list of {@link TextEntry}. */
-// TODO(b/242631897): Resolve nullness suppression.
-@SuppressWarnings("nullness")
 @VisibleForTesting
 public class MdnsTextRecord extends MdnsRecord {
     private List<TextEntry> entries;
@@ -90,7 +90,7 @@
     }
 
     @Override
-    public boolean equals(Object other) {
+    public boolean equals(@Nullable Object other) {
         if (this == other) {
             return true;
         }
diff --git a/service/mdns/com/android/server/connectivity/mdns/util/MdnsLogger.java b/service/mdns/com/android/server/connectivity/mdns/util/MdnsLogger.java
index 431f1fd..63107e5 100644
--- a/service/mdns/com/android/server/connectivity/mdns/util/MdnsLogger.java
+++ b/service/mdns/com/android/server/connectivity/mdns/util/MdnsLogger.java
@@ -16,6 +16,7 @@
 
 package com.android.server.connectivity.mdns.util;
 
+import android.annotation.Nullable;
 import android.text.TextUtils;
 
 import com.android.net.module.util.SharedLog;
@@ -40,7 +41,7 @@
         mLog.log(message);
     }
 
-    public void log(String message, Object... args) {
+    public void log(String message, @Nullable Object... args) {
         mLog.log(message + " ; " + TextUtils.join(" ; ", args));
     }
 
diff --git a/tests/unit/java/com/android/server/connectivity/mdns/MdnsSocketTests.java b/tests/unit/java/com/android/server/connectivity/mdns/MdnsSocketTests.java
index 9f11a4b..73dbd38 100644
--- a/tests/unit/java/com/android/server/connectivity/mdns/MdnsSocketTests.java
+++ b/tests/unit/java/com/android/server/connectivity/mdns/MdnsSocketTests.java
@@ -53,7 +53,7 @@
     private SocketAddress socketIPv4Address;
     private SocketAddress socketIPv6Address;
 
-    private byte[] data = new byte[25];
+    private final byte[] data = new byte[25];
     private final DatagramPacket datagramPacket = new DatagramPacket(data, data.length);
     private NetworkInterface networkInterface;
 
@@ -74,14 +74,8 @@
     }
 
     @Test
-    public void testMdnsSocket() throws IOException {
-        mdnsSocket =
-                new MdnsSocket(mockMulticastNetworkInterfaceProvider, MdnsConstants.MDNS_PORT) {
-                    @Override
-                    MulticastSocket createMulticastSocket(int port) throws IOException {
-                        return mockMulticastSocket;
-                    }
-                };
+    public void mdnsSocket_basicFunctionality() throws IOException {
+        mdnsSocket = new MdnsSocket(mockMulticastNetworkInterfaceProvider, mockMulticastSocket);
         mdnsSocket.send(datagramPacket);
         verify(mockMulticastSocket).setNetworkInterface(networkInterface);
         verify(mockMulticastSocket).send(datagramPacket);
@@ -100,20 +94,14 @@
     }
 
     @Test
-    public void testIPv6OnlyNetwork_IPv6Enabled() throws IOException {
+    public void ipv6OnlyNetwork_ipv6Enabled() throws IOException {
         // Have mockMulticastNetworkInterfaceProvider send back an IPv6Only networkInterfaceWrapper
         networkInterface = createEmptyNetworkInterface();
         when(mockNetworkInterfaceWrapper.getNetworkInterface()).thenReturn(networkInterface);
         when(mockMulticastNetworkInterfaceProvider.getMulticastNetworkInterfaces())
                 .thenReturn(Collections.singletonList(mockNetworkInterfaceWrapper));
 
-        mdnsSocket =
-                new MdnsSocket(mockMulticastNetworkInterfaceProvider, MdnsConstants.MDNS_PORT) {
-                    @Override
-                    MulticastSocket createMulticastSocket(int port) throws IOException {
-                        return mockMulticastSocket;
-                    }
-                };
+        mdnsSocket = new MdnsSocket(mockMulticastNetworkInterfaceProvider, mockMulticastSocket);
 
         when(mockMulticastNetworkInterfaceProvider.isOnIpV6OnlyNetwork(
                 Collections.singletonList(mockNetworkInterfaceWrapper)))
@@ -130,20 +118,14 @@
     }
 
     @Test
-    public void testIPv6OnlyNetwork_IPv6Toggle() throws IOException {
+    public void ipv6OnlyNetwork_ipv6Toggle() throws IOException {
         // Have mockMulticastNetworkInterfaceProvider send back a networkInterfaceWrapper
         networkInterface = createEmptyNetworkInterface();
         when(mockNetworkInterfaceWrapper.getNetworkInterface()).thenReturn(networkInterface);
         when(mockMulticastNetworkInterfaceProvider.getMulticastNetworkInterfaces())
                 .thenReturn(Collections.singletonList(mockNetworkInterfaceWrapper));
 
-        mdnsSocket =
-                new MdnsSocket(mockMulticastNetworkInterfaceProvider, MdnsConstants.MDNS_PORT) {
-                    @Override
-                    MulticastSocket createMulticastSocket(int port) throws IOException {
-                        return mockMulticastSocket;
-                    }
-                };
+        mdnsSocket = new MdnsSocket(mockMulticastNetworkInterfaceProvider, mockMulticastSocket);
 
         when(mockMulticastNetworkInterfaceProvider.isOnIpV6OnlyNetwork(
                 Collections.singletonList(mockNetworkInterfaceWrapper)))