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
1 file changed