[hueemulation] Fix broken fallback address (openhab#7305)

With the changes in openhab#6967 the HueEmulationServiceOSGiTest always fails for me.
The reason is that if the discoveryIps are not configured, it is no longer guaranteed it will use the primary IPv4 host address as fallback.
In my case the iterator on the HashSet would return an IPv6 address as first address.
By using a LinkedHashSet the order is preserved and it will again use the primary IPv4 host address as fallback.

Signed-off-by: Wouter Born <[email protected]>
Signed-off-by: Daan Meijer <[email protected]>

bundles/org.openhab.io.hueemulation/src/main/java/org/openhab/io/hueemulation/internal/ConfigStore.java

@@ -15,7 +15,7 @@
 import java.net.InetAddress;
 import java.net.UnknownHostException;
 import java.util.Collections;
-import java.util.HashSet;
+import java.util.LinkedHashSet;
 import java.util.Map;
 import java.util.Set;
 import java.util.UUID;
@@ -197,7 +197,7 @@ public void modified(Map<String, Object> properties) {
             discoveryIps = Collections.unmodifiableSet(Stream.of(config.discoveryIps.split(",")).map(String::trim)
                     .map(this::byName).filter(e -> e != null).collect(Collectors.toSet()));
         } else {
-            discoveryIps = new HashSet<>();
+            discoveryIps = new LinkedHashSet<>();
             configuredAddress = byName(networkAddressService.getPrimaryIpv4HostAddress());
             if (configuredAddress != null) {
                 discoveryIps.add(configuredAddress);
@@ -211,7 +211,7 @@ public void modified(Map<String, Object> properties) {
             }
         }
 
-        if (discoveryIps.size() < 1) {
+        if (discoveryIps.isEmpty()) {
             try {
                 logger.info("No discovery ip specified. Trying to determine the host address");
                 configuredAddress = InetAddress.getLocalHost();
@@ -318,7 +318,7 @@ public String mapItemUIDtoHueID(Item item) {
     }
 
     public boolean isReady() {
-        return discoveryIps.size() > 0;
+        return !discoveryIps.isEmpty();
     }
 
     public HueEmulationConfig getConfig() {