8035633: TEST_BUG: java/net/NetworkInterface/Equals.java and some tests failed on windows intermittently

Reviewed-by: chegar, alanb, igerasim
diff --git a/jdk/test/java/net/MulticastSocket/TestInterfaces.java b/jdk/test/java/net/MulticastSocket/TestInterfaces.java
index cb8c6b0..1d87d8d 100644
--- a/jdk/test/java/net/MulticastSocket/TestInterfaces.java
+++ b/jdk/test/java/net/MulticastSocket/TestInterfaces.java
@@ -87,8 +87,9 @@
                 continue;
             }
 
-            // JDK-8022963, Skip (Windows) Teredo Tunneling seudo-Interface
-            if (isWindows && ni.getDisplayName().contains("Teredo"))
+            // JDK-8022963, Skip (Windows) Teredo Tunneling Pseudo-Interface
+            String dName = ni.getDisplayName();
+            if (isWindows && dName != null && dName.contains("Teredo"))
                 continue;
 
             NetworkInterface curr = soc.getNetworkInterface();
diff --git a/jdk/test/java/net/NetworkInterface/Equals.java b/jdk/test/java/net/NetworkInterface/Equals.java
index 13dc5fc..8cc81f8 100644
--- a/jdk/test/java/net/NetworkInterface/Equals.java
+++ b/jdk/test/java/net/NetworkInterface/Equals.java
@@ -62,8 +62,9 @@
         while (nifs2.hasMoreElements()) {
             NetworkInterface ni = nifs2.nextElement();
 
-            // JDK-8022963, Skip (Windows)Teredo Tunneling seudo-Interface
-            if (isWindows && ni.getDisplayName().contains("Teredo"))
+            // JDK-8022963, Skip (Windows)Teredo Tunneling Pseudo-Interface
+            String dName = ni.getDisplayName();
+            if (isWindows && dName != null && dName.contains("Teredo"))
                 continue;
 
             NetworkInterface niOrig = nicMap.get(ni.getName());
diff --git a/jdk/test/java/net/NetworkInterface/IndexTest.java b/jdk/test/java/net/NetworkInterface/IndexTest.java
index 58ebb16..a1c65aa 100644
--- a/jdk/test/java/net/NetworkInterface/IndexTest.java
+++ b/jdk/test/java/net/NetworkInterface/IndexTest.java
@@ -40,8 +40,9 @@
         NetworkInterface nif;
         while (netifs.hasMoreElements()) {
             nif = netifs.nextElement();
-            // JDK-8022212, Skip (Windows) Teredo Tunneling seudo-Interface
-            if (nif.getDisplayName().contains("Teredo") && isWindows)
+            // JDK-8022212, Skip (Windows) Teredo Tunneling Pseudo-Interface
+            String dName = nif.getDisplayName();
+            if (isWindows && dName != null && dName.contains("Teredo"))
                 continue;
             int index = nif.getIndex();
             if (index >= 0) {