another comparison fix

java/src/com/zerotier/sdk/VirtualNetworkConfig.java

@@ -152,7 +152,9 @@ public final class VirtualNetworkConfig implements Comparable<VirtualNetworkConf
         }
 
         boolean dnsEquals = false;
-        if (this.dns != null && cfg.dns != null) {
+        if (this.dns == null || cfg.dns == null) {
+            dnsEquals = true;
+        } else if (this.dns != null) {
             dnsEquals = this.dns.equals(cfg.dns);
         }
 

java/src/com/zerotier/sdk/VirtualNetworkDNS.java

@@ -15,6 +15,7 @@ public class VirtualNetworkDNS implements Comparable<VirtualNetworkDNS> {
     public VirtualNetworkDNS() {}
 
     public boolean equals(VirtualNetworkDNS o) {
+        if (o == null) return false;
         return domain.equals(o.domain) && servers.equals(o.servers);
     }