[ST02.2] Use the getters of DnsHeader

Bug: 139774492
Test: atest DnsPacketTest DnsResolverTest
Change-Id: Ib5616c65cce9668e7c6a00571c34ece7b4d8ab39
diff --git a/framework/src/android/net/DnsResolver.java b/framework/src/android/net/DnsResolver.java
index 382a9de..33722fc 100644
--- a/framework/src/android/net/DnsResolver.java
+++ b/framework/src/android/net/DnsResolver.java
@@ -544,7 +544,7 @@
 
         DnsAddressAnswer(@NonNull byte[] data) throws ParseException {
             super(data);
-            if ((mHeader.flags & (1 << 15)) == 0) {
+            if ((mHeader.getFlags() & (1 << 15)) == 0) {
                 throw new ParseException("Not an answer packet");
             }
             if (mHeader.getRecordCount(QDSECTION) == 0) {