Fix IpPrefixTest#testContainsInetAddress fail.

The argument of IpPreFix#contains() has been marked as @NonNull.
So the IpPrefixTest#testContainsInetAddress should not test
contains() method wiht null object.

Bug: None
Test: atest FrameworksNetTests
      atest IpPrefixTest#testContainsInetAddress

Change-Id: I2f6bee19514dc47702f64d2a2bbf02d8b7b1b407
diff --git a/tests/net/java/android/net/IpPrefixTest.java b/tests/net/java/android/net/IpPrefixTest.java
index 3cc0e36..abf019a 100644
--- a/tests/net/java/android/net/IpPrefixTest.java
+++ b/tests/net/java/android/net/IpPrefixTest.java
@@ -231,7 +231,6 @@
         assertFalse(p.contains(Address("2001:db8:f00::ace:d00e")));
         assertFalse(p.contains(Address("2001:db8:f00::bad:d00d")));
         assertFalse(p.contains(Address("2001:4868:4860::8888")));
-        assertFalse(p.contains((InetAddress)null));
         assertFalse(p.contains(Address("8.8.8.8")));
 
         p = new IpPrefix("192.0.2.0/23");