Fix shouldPreserveAddressOrderOnInsertions test

The test failed because the ArrayList - in contrast
to the underlying Set - did not check for duplicates
on insert. Under certain circumstances this lead to
an index out of bounds exception because the list in
the test contained duplicated entries which were not
present in the set of the Socks5Proxy.
I fixed the issue by only inserting the address when
it was not in the list before.

smack-extensions/src/test/java/org/jivesoftware/smackx/bytestreams/socks5/Socks5ProxyTest.java

@@ -30,6 +30,8 @@ import java.net.Socket;
 import java.net.SocketException;
 import java.net.UnknownHostException;
 import java.util.ArrayList;
+import java.util.Iterator;
+import java.util.LinkedHashSet;
 import java.util.List;
 
 import org.jivesoftware.smack.util.StringUtils;
@@ -102,13 +104,11 @@ public class Socks5ProxyTest {
     @Test
     public void shouldPreserveAddressOrderOnInsertions() {
         Socks5Proxy proxy = Socks5Proxy.getSocks5Proxy();
-        List<String> addresses = new ArrayList<>(proxy.getLocalAddresses());
+
+        LinkedHashSet<String> addresses = new LinkedHashSet<>(proxy.getLocalAddresses());
 
         for (int i = 1 ; i <= 3; i++) {
-            String addr = Integer.toString(i);
-            if (!addresses.contains(addr)) {
-                addresses.add(addr);
-            }
+            addresses.add(Integer.toString(i));
         }
 
         for (String address : addresses) {
@@ -116,8 +116,10 @@ public class Socks5ProxyTest {
         }
 
         List<String> localAddresses = proxy.getLocalAddresses();
+
+        Iterator<String> iterator = addresses.iterator();
         for (int i = 0; i < addresses.size(); i++) {
-            assertEquals(addresses.get(i), localAddresses.get(i));
+            assertEquals(iterator.next(), localAddresses.get(i));
         }
     }