Migrate frameworks/base/tests/net/ to androidx.test

Test: atest FrameworksNetTests
Change-Id: Iaa59d606f5e1678cc5aaca9ed37e184fad894e5d
diff --git a/tests/net/java/android/net/IpPrefixTest.java b/tests/net/java/android/net/IpPrefixTest.java
index 1f1ba2e..3cc0e36 100644
--- a/tests/net/java/android/net/IpPrefixTest.java
+++ b/tests/net/java/android/net/IpPrefixTest.java
@@ -25,15 +25,16 @@
 import static org.junit.Assert.fail;
 
 import android.os.Parcel;
-import android.support.test.filters.SmallTest;
-import android.support.test.runner.AndroidJUnit4;
+
+import androidx.test.filters.SmallTest;
+import androidx.test.runner.AndroidJUnit4;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
 
 import java.net.InetAddress;
 import java.util.Random;
 
-import org.junit.runner.RunWith;
-import org.junit.Test;
-
 @RunWith(AndroidJUnit4.class)
 @SmallTest
 public class IpPrefixTest {