API review: access field by method

- InvalidPacketException, public field should be a method so
  add getter to get error code.
- KeepalivePacketData, public fields should be methods so
   add getter for fields.

Bug: 151322799
Test: atest FrameworksNetTests
      atest FrameworksWifiTests
      atest FrameworksTelephonyTests: some failure in CarrierAppUtilsTest
Copy from ag/10731108
Change-Id: Id01e6135193716cc21bba11da529bf1507a954f7
Merged-In: Id01e6135193716cc21bba11da529bf1507a954f7

core/java/android/net/KeepalivePacketData.java

@@ -19,6 +19,7 @@ package android.net;
 import static android.net.InvalidPacketException.ERROR_INVALID_IP_ADDRESS;
 import static android.net.InvalidPacketException.ERROR_INVALID_PORT;
 
+import android.annotation.IntRange;
 import android.annotation.NonNull;
 import android.annotation.SystemApi;
 import android.net.util.IpUtils;
@@ -37,17 +38,17 @@ public class KeepalivePacketData {
 
     /** Source IP address */
     @NonNull
-    public final InetAddress srcAddress;
+    private final InetAddress mSrcAddress;
 
     /** Destination IP address */
     @NonNull
-    public final InetAddress dstAddress;
+    private final InetAddress mDstAddress;
 
     /** Source port */
-    public final int srcPort;
+    private final int mSrcPort;
 
     /** Destination port */
-    public final int dstPort;
+    private final int mDstPort;
 
     /** Packet data. A raw byte string of packet data, not including the link-layer header. */
     private final byte[] mPacket;
@@ -60,13 +61,14 @@ public class KeepalivePacketData {
     /**
      * A holding class for data necessary to build a keepalive packet.
      */
-    protected KeepalivePacketData(@NonNull InetAddress srcAddress, int srcPort,
-            @NonNull InetAddress dstAddress, int dstPort,
-                    @NonNull byte[] data) throws InvalidPacketException {
-        this.srcAddress = srcAddress;
-        this.dstAddress = dstAddress;
-        this.srcPort = srcPort;
-        this.dstPort = dstPort;
+    protected KeepalivePacketData(@NonNull InetAddress srcAddress,
+            @IntRange(from = 0, to = 65535) int srcPort, @NonNull InetAddress dstAddress,
+            @IntRange(from = 0, to = 65535) int dstPort,
+            @NonNull byte[] data) throws InvalidPacketException {
+        this.mSrcAddress = srcAddress;
+        this.mDstAddress = dstAddress;
+        this.mSrcPort = srcPort;
+        this.mDstPort = dstPort;
         this.mPacket = data;
 
         // Check we have two IP addresses of the same family.
@@ -83,6 +85,31 @@ public class KeepalivePacketData {
         }
     }
 
+    /** Get source IP address. */
+    @NonNull
+    public InetAddress getSrcAddress() {
+        return mSrcAddress;
+    }
+
+    /** Get destination IP address. */
+    @NonNull
+    public InetAddress getDstAddress() {
+        return mDstAddress;
+    }
+
+    /** Get source port number. */
+    public int getSrcPort() {
+        return mSrcPort;
+    }
+
+    /** Get destination port number. */
+    public int getDstPort() {
+        return mDstPort;
+    }
+
+    /**
+     * Returns a byte array of the given packet data.
+     */
     @NonNull
     public byte[] getPacket() {
         return mPacket.clone();