[hue] Fix compiler warnings (#15419)

* Fix compiler warnings
* Fix integration test compiler/SAT warnings

Signed-off-by: Jacob Laursen <jacob-github@vindvejr.dk>

bundles/org.openhab.binding.hue/src/main/java/org/openhab/binding/hue/internal/config/HueBridgeConfig.java

@@ -14,10 +14,9 @@ package org.openhab.binding.hue.internal.config;
 
 import org.eclipse.jdt.annotation.NonNullByDefault;
 import org.eclipse.jdt.annotation.Nullable;
-import org.openhab.binding.hue.internal.handler.HueBridgeHandler;
 
 /**
- * Configuration for the {@link HueBridgeHandler}.
+ * Configuration for the {@link org.openhab.binding.hue.internal.handler.HueBridgeHandler}.
  *
  * @author Christoph Weitkamp - Initial contribution
  */

bundles/org.openhab.binding.hue/src/main/java/org/openhab/binding/hue/internal/connection/HueBridge.java

@@ -996,7 +996,12 @@ public class HueBridge {
     // Methods that convert gson exceptions into ApiExceptions
     private <T> T safeFromJson(String json, Type typeOfT) throws ApiException {
         try {
-            return gson.fromJson(json, typeOfT);
+            @Nullable
+            T safe = gson.fromJson(json, typeOfT);
+            if (safe == null) {
+                throw new ApiException("JSON is null or empty");
+            }
+            return safe;
         } catch (JsonParseException e) {
             throw new ApiException("API returned unexpected result: " + e.getMessage());
         }
@@ -1004,7 +1009,12 @@ public class HueBridge {
 
     private <T> T safeFromJson(String json, Class<T> classOfT) throws ApiException {
         try {
-            return gson.fromJson(json, classOfT);
+            @Nullable
+            T safe = gson.fromJson(json, classOfT);
+            if (safe == null) {
+                throw new ApiException("JSON is null or empty");
+            }
+            return safe;
         } catch (JsonParseException e) {
             throw new ApiException("API returned unexpected result: " + e.getMessage());
         }

bundles/org.openhab.binding.hue/src/main/java/org/openhab/binding/hue/internal/discovery/BridgeJsonParameters.java

@@ -12,6 +12,9 @@
  */
 package org.openhab.binding.hue.internal.discovery;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.jdt.annotation.Nullable;
+
 import com.google.gson.annotations.SerializedName;
 
 /**
@@ -22,15 +25,17 @@ import com.google.gson.annotations.SerializedName;
  * @author Awelkiyar Wehabrebi - Initial contribution and API
  * @author Christoph Knauf - Refactorings
  */
+@NonNullByDefault
 public class BridgeJsonParameters {
 
-    private String id;
+    private @Nullable String id;
     @SerializedName("internalipaddress")
-    private String internalIpAddress;
+    private @Nullable String internalIpAddress;
     @SerializedName("macaddress")
-    private String macAddress;
+    private @Nullable String macAddress;
-    private String name;
+    private @Nullable String name;
 
+    @SuppressWarnings("unused")
     private BridgeJsonParameters() {
         // This no arguments constructor is required for Gson deserialization
     }
@@ -42,19 +47,19 @@ public class BridgeJsonParameters {
         this.name = name;
     }
 
-    public String getInternalIpAddress() {
+    public @Nullable String getInternalIpAddress() {
         return internalIpAddress;
     }
 
-    public String getId() {
+    public @Nullable String getId() {
         return id;
     }
 
-    public String getMacAddress() {
+    public @Nullable String getMacAddress() {
         return macAddress;
     }
 
-    public String getName() {
+    public @Nullable String getName() {
         return name;
     }
 }

bundles/org.openhab.binding.hue/src/main/java/org/openhab/binding/hue/internal/discovery/HueBridgeNupnpDiscovery.java

@@ -80,9 +80,18 @@ public class HueBridgeNupnpDiscovery extends AbstractDiscoveryService {
      */
     private void discoverHueBridges() {
         for (BridgeJsonParameters bridge : getBridgeList()) {
-            if (isReachableAndValidHueBridge(bridge)) {
+            if (!isReachableAndValidHueBridge(bridge)) {
+                continue;
+            }
             String host = bridge.getInternalIpAddress();
-                String serialNumber = bridge.getId().toLowerCase();
+            if (host == null) {
+                continue;
+            }
+            String id = bridge.getId();
+            if (id == null) {
+                continue;
+            }
+            String serialNumber = id.toLowerCase();
             ThingUID uid = new ThingUID(THING_TYPE_BRIDGE, serialNumber);
             ThingUID legacyUID = null;
             String label = String.format(DISCOVERY_LABEL_PATTERN, host);
@@ -111,7 +120,6 @@ public class HueBridgeNupnpDiscovery extends AbstractDiscoveryService {
             thingDiscovered(builder.build());
         }
     }
-    }
 
     /**
      * Checks if the Bridge is a reachable Hue Bridge with a valid id.

bundles/org.openhab.binding.hue/src/main/java/org/openhab/binding/hue/internal/discovery/HueBridgeUPNPDiscoveryParticipant.java

@@ -32,7 +32,6 @@ import org.openhab.core.config.discovery.DiscoveryResult;
 import org.openhab.core.config.discovery.DiscoveryResultBuilder;
 import org.openhab.core.config.discovery.DiscoveryService;
 import org.openhab.core.config.discovery.upnp.UpnpDiscoveryParticipant;
-import org.openhab.core.config.discovery.upnp.internal.UpnpDiscoveryService;
 import org.openhab.core.thing.Thing;
 import org.openhab.core.thing.ThingTypeUID;
 import org.openhab.core.thing.ThingUID;
@@ -45,7 +44,7 @@ import org.slf4j.LoggerFactory;
 
 /**
  * The {@link HueBridgeUPNPDiscoveryParticipant} is responsible for discovering new and removed Hue Bridges. It uses the
- * central {@link UpnpDiscoveryService}.
+ * central {@link org.openhab.core.config.discovery.upnp.internal.UpnpDiscoveryService}.
  *
  * The discovery through UPnP was replaced by mDNS discovery for recent bridges (V2).
  * For old bridges (V1), the UPnP discovery is still required (as mDNS is not implemented).

bundles/org.openhab.binding.hue/src/main/java/org/openhab/binding/hue/internal/dto/ApiVersion.java

@@ -12,7 +12,6 @@
  */
 package org.openhab.binding.hue.internal.dto;
 
-import java.util.Comparator;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
@@ -77,7 +76,7 @@ public class ApiVersion {
     }
 
     /**
-     * compare API versions according to {@link Comparator#compare(Object, Object)}
+     * compare API versions according to {@link java.util.Comparator#compare(Object, Object)}
      *
      * @param other
      * @return

bundles/org.openhab.binding.hue/src/main/java/org/openhab/binding/hue/internal/dto/Config.java

@@ -17,6 +17,8 @@ import java.util.Date;
 import java.util.List;
 import java.util.Map;
 
+import com.google.gson.annotations.SerializedName;
+
 /**
  * Detailed bridge info available if authenticated.
  *
@@ -37,7 +39,8 @@ public class Config {
     private String gateway;
     private String proxyaddress;
     private int proxyport;
-    private Date UTC;
+    @SerializedName("UTC")
+    private Date utc;
     private boolean linkbutton;
     private Map<String, User> whitelist;
     private SoftwareUpdate swupdate;
@@ -150,7 +153,7 @@ public class Config {
      * @return time on the bridge
      */
     public Date getUTCTime() {
-        return UTC;
+        return utc;
     }
 
     /**

bundles/org.openhab.binding.hue/src/main/java/org/openhab/binding/hue/internal/dto/FullConfig.java

@@ -35,8 +35,9 @@ public class FullConfig {
     public List<FullLight> getLights() {
         ArrayList<FullLight> lightsList = new ArrayList<>();
 
-        for (String id : lights.keySet()) {
+        for (Map.Entry<String, FullLight> entry : lights.entrySet()) {
-            FullLight light = lights.get(id);
+            String id = entry.getKey();
+            FullLight light = entry.getValue();
             light.setId(id);
             lightsList.add(light);
         }
@@ -52,8 +53,9 @@ public class FullConfig {
     public List<FullGroup> getGroups() {
         ArrayList<FullGroup> groupsList = new ArrayList<>();
 
-        for (String id : groups.keySet()) {
+        for (Map.Entry<String, FullGroup> entry : groups.entrySet()) {
-            FullGroup group = groups.get(id);
+            String id = entry.getKey();
+            FullGroup group = entry.getValue();
             group.setId(id);
             groupsList.add(group);
         }

bundles/org.openhab.binding.hue/src/main/java/org/openhab/binding/hue/internal/dto/FullGroup.java

@@ -13,9 +13,13 @@
 package org.openhab.binding.hue.internal.dto;
 
 import java.lang.reflect.Type;
+import java.util.ArrayList;
 import java.util.List;
 import java.util.Map;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.jdt.annotation.Nullable;
+
 import com.google.gson.reflect.TypeToken;
 
 /**
@@ -25,13 +29,14 @@ import com.google.gson.reflect.TypeToken;
  * @author Denis Dudnik - moved Jue library source code inside the smarthome Hue binding
  * @author Laurent Garnier - field state added
  */
+@NonNullByDefault
 public class FullGroup extends Group {
     public static final Type GSON_TYPE = new TypeToken<Map<String, FullGroup>>() {
     }.getType();
 
-    private State action;
+    private @Nullable State action;
-    private List<String> lights;
+    private @Nullable List<String> lights;
-    private State groupState; // Will not be set by hue API
+    private @Nullable State groupState; // Will not be set by hue API
 
     FullGroup() {
         super();
@@ -53,7 +58,7 @@ public class FullGroup extends Group {
      *
      * @return last state update
      */
-    public State getAction() {
+    public @Nullable State getAction() {
         return action;
     }
 
@@ -63,7 +68,8 @@ public class FullGroup extends Group {
      * @return lights in the group
      */
     public List<String> getLightIds() {
-        return lights;
+        List<String> lights = this.lights;
+        return lights != null ? lights : new ArrayList<>();
     }
 
     /**
@@ -72,6 +78,10 @@ public class FullGroup extends Group {
      * @return current state
      */
     public State getState() {
+        State groupState = this.groupState;
+        if (groupState == null) {
+            throw new IllegalStateException("Group state not initialized when requested");
+        }
         return groupState;
     }
 

bundles/org.openhab.binding.hue/src/main/java/org/openhab/binding/hue/internal/dto/FullHueObject.java

@@ -67,6 +67,7 @@ public class FullHueObject extends HueObject {
     }
 
     public @Nullable String getNormalizedModelID() {
+        String modelid = this.modelid;
         return modelid != null ? modelid.replaceAll(NORMALIZE_ID_REGEX, "_") : modelid;
     }
 

bundles/org.openhab.binding.hue/src/main/java/org/openhab/binding/hue/internal/dto/Scene.java

@@ -13,6 +13,7 @@
 package org.openhab.binding.hue.internal.dto;
 
 import java.lang.reflect.Type;
+import java.util.ArrayList;
 import java.util.List;
 import java.util.Map;
 
@@ -36,7 +37,7 @@ public class Scene {
     private @NonNullByDefault({}) String id;
     private @NonNullByDefault({}) String name;
     @SerializedName("lights")
-    private @NonNullByDefault({}) List<String> lightIds;
+    private @Nullable List<String> lightIds;
     @SerializedName("group")
     private @Nullable String groupId;
     private boolean recycle;
@@ -84,7 +85,8 @@ public class Scene {
      * @return list of lights that the scene applies to
      */
     public List<String> getLightIds() {
-        return lightIds;
+        List<String> lightIds = this.lightIds;
+        return lightIds != null ? lightIds : new ArrayList<String>();
     }
 
     /**
@@ -141,11 +143,11 @@ public class Scene {
      * </ol>
      */
     public boolean isApplicableTo(FullGroup group) {
-        if (getGroupId() == null) {
+        String groupId = this.groupId;
+        if (groupId == null) {
             return getLightIds().stream().allMatch(id -> group.getLightIds().contains(id));
         } else {
-            String groupId = getGroupId();
+            return group.getId().contentEquals(groupId);
-            return groupId != null ? group.getId().contentEquals(groupId) : false;
         }
     }
 

bundles/org.openhab.binding.hue/src/main/java/org/openhab/binding/hue/internal/dto/SearchForLightsRequest.java

@@ -14,22 +14,23 @@ package org.openhab.binding.hue.internal.dto;
 
 import java.util.List;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
+
 /**
  *
  * @author Q42 - Initial contribution
  * @author Andre Fuechsel - search for lights with given serial number added
  * @author Denis Dudnik - moved Jue library source code inside the smarthome Hue binding
  */
-@SuppressWarnings("unused")
+@NonNullByDefault
 public class SearchForLightsRequest {
+    @SuppressWarnings("unused")
     private List<String> deviceid;
 
     public SearchForLightsRequest(List<String> deviceid) {
-        if (deviceid != null && (deviceid.isEmpty() || deviceid.size() > 16)) {
+        if (deviceid.isEmpty() || deviceid.size() > 16) {
             throw new IllegalArgumentException("Group cannot be empty and cannot have more than 16 lights");
         }
-        if (deviceid != null) {
         this.deviceid = deviceid;
     }
-    }
 }

bundles/org.openhab.binding.hue/src/main/java/org/openhab/binding/hue/internal/dto/SetAttributesRequest.java

@@ -13,7 +13,6 @@
 package org.openhab.binding.hue.internal.dto;
 
 import java.util.List;
-import java.util.stream.Collectors;
 
 import org.eclipse.jdt.annotation.NonNullByDefault;
 import org.eclipse.jdt.annotation.Nullable;
@@ -45,6 +44,6 @@ public class SetAttributesRequest {
         }
 
         this.name = name;
-        this.lights = lights == null ? null : lights.stream().map(l -> l.getId()).collect(Collectors.toList());
+        this.lights = lights == null ? null : lights.stream().map(l -> l.getId()).toList();
     }
 }

bundles/org.openhab.binding.hue/src/main/java/org/openhab/binding/hue/internal/handler/HueBridgeHandler.java

@@ -235,7 +235,7 @@ public class HueBridgeHandler extends ConfigStatusBridgeHandler implements HueCl
                     sensorStatusListener.onSensorRemoved();
                 }
 
-                if (discovery != null && sensor != null) {
+                if (discovery != null) {
                     discovery.removeSensorDiscovery(sensor);
                 }
             });
@@ -295,7 +295,7 @@ public class HueBridgeHandler extends ConfigStatusBridgeHandler implements HueCl
                     lightStatusListener.onLightRemoved();
                 }
 
-                if (discovery != null && light != null) {
+                if (discovery != null) {
                     discovery.removeLightDiscovery(light);
                 }
             });
@@ -385,7 +385,7 @@ public class HueBridgeHandler extends ConfigStatusBridgeHandler implements HueCl
                     groupStatusListener.onGroupRemoved();
                 }
 
-                if (discovery != null && group != null) {
+                if (discovery != null) {
                     discovery.removeGroupDiscovery(group);
                 }
             });
@@ -402,12 +402,11 @@ public class HueBridgeHandler extends ConfigStatusBridgeHandler implements HueCl
         private void setBridgeSceneChannelStateOptions(List<Scene> scenes, Map<String, FullGroup> groups) {
             Map<String, String> groupNames = groups.entrySet().stream()
                     .collect(Collectors.toMap(Map.Entry::getKey, e -> e.getValue().getName()));
-            List<StateOption> stateOptions = scenes.stream().map(scene -> scene.toStateOption(groupNames))
+            List<StateOption> stateOptions = scenes.stream().map(scene -> scene.toStateOption(groupNames)).toList();
-                    .collect(Collectors.toList());
             stateDescriptionOptionProvider.setStateOptions(new ChannelUID(getThing().getUID(), CHANNEL_SCENE),
                     stateOptions);
             consoleScenesList = scenes.stream().map(scene -> "Id is \"" + scene.getId() + "\" for scene \""
-                    + scene.toStateOption(groupNames).getLabel() + "\"").collect(Collectors.toList());
+                    + scene.toStateOption(groupNames).getLabel() + "\"").toList();
         }
     };
 

bundles/org.openhab.binding.hue/src/main/java/org/openhab/binding/hue/internal/handler/HueGroupHandler.java

@@ -455,11 +455,11 @@ public class HueGroupHandler extends BaseThingHandler implements HueLightActions
             FullGroup group = handler.getGroupById(groupId);
             if (group != null) {
                 stateOptions = updatedScenes.stream().filter(scene -> scene.isApplicableTo(group))
-                        .map(Scene::toStateOption).collect(Collectors.toList());
+                        .map(Scene::toStateOption).toList();
-                consoleScenesList = updatedScenes
+                consoleScenesList = updatedScenes.stream().filter(scene -> scene.isApplicableTo(group))
-                        .stream().filter(scene -> scene.isApplicableTo(group)).map(scene -> "Id is \"" + scene.getId()
+                        .map(scene -> "Id is \"" + scene.getId() + "\" for scene \"" + scene.toStateOption().getLabel()
-                                + "\" for scene \"" + scene.toStateOption().getLabel() + "\"")
+                                + "\"")
-                        .collect(Collectors.toList());
+                        .toList();
             }
         }
         stateDescriptionOptionProvider.setStateOptions(new ChannelUID(getThing().getUID(), CHANNEL_SCENE),

bundles/org.openhab.binding.hue/src/main/java/org/openhab/binding/hue/internal/handler/HueStateDescriptionProvider.java

@@ -58,6 +58,7 @@ public class HueStateDescriptionProvider extends BaseDynamicStateDescriptionProv
         StateDescriptionFragment oldStateDescriptionFragment = stateDescriptionFragments.get(channelUID);
         if (!stateDescriptionFragment.equals(oldStateDescriptionFragment)) {
             stateDescriptionFragments.put(channelUID, stateDescriptionFragment);
+            ItemChannelLinkRegistry itemChannelLinkRegistry = this.itemChannelLinkRegistry;
             postEvent(ThingEventFactory.createChannelDescriptionChangedEvent(channelUID,
                     itemChannelLinkRegistry != null ? itemChannelLinkRegistry.getLinkedItemNames(channelUID) : Set.of(),
                     stateDescriptionFragment, oldStateDescriptionFragment));

bundles/org.openhab.binding.hue/src/main/java/org/openhab/binding/hue/internal/handler/LightStateConverter.java

@@ -30,6 +30,7 @@ import org.openhab.core.library.types.PercentType;
 import org.openhab.core.library.types.QuantityType;
 import org.openhab.core.library.types.StringType;
 import org.openhab.core.library.unit.Units;
+import org.openhab.core.util.ColorUtil;
 
 /**
  * The {@link LightStateConverter} is responsible for mapping to/from jue types.
@@ -276,7 +277,7 @@ public class LightStateConverter {
 
     private static HSBType fromXYtoHSBType(State lightState) {
         float[] xy = lightState.getXY();
-        HSBType hsb = HSBType.fromXY(xy[0], xy[1]);
+        HSBType hsb = ColorUtil.xyToHsb(new double[] { xy[0], xy[1] });
 
         int brightnessInPercent = (int) Math.ceil(lightState.getBrightness() / BRIGHTNESS_FACTOR);
         brightnessInPercent = restrictToBounds(brightnessInPercent);

bundles/org.openhab.binding.hue/src/test/java/org/openhab/binding/hue/internal/SceneTest.java

@@ -15,7 +15,6 @@ package org.openhab.binding.hue.internal;
 import static org.hamcrest.CoreMatchers.is;
 import static org.hamcrest.MatcherAssert.assertThat;
 
-import java.util.Arrays;
 import java.util.List;
 
 import org.eclipse.jdt.annotation.NonNullByDefault;
@@ -39,7 +38,7 @@ public class SceneTest {
     @Test
     public void testIsApplicableToHasGroupIdMatchingGroup() {
         String groupId = "groupId";
-        List<String> lights = Arrays.asList("1", "2");
+        List<String> lights = List.of("1", "2");
 
         Scene scene = new Scene(PLACEHOLDER, PLACEHOLDER, groupId, lights, false);
         FullGroup group = new FullGroup(groupId, PLACEHOLDER, PLACEHOLDER, PLACEHOLDER_STATE, lights,
@@ -56,8 +55,8 @@ public class SceneTest {
     public void testIsApplicableToHasGroupIdNotMatchingGroup() {
         String groupId = "groupId";
         String otherGroupId = "otherGroupId";
-        List<String> lights = Arrays.asList("1", "2");
+        List<String> lights = List.of("1", "2");
-        List<String> otherLights = Arrays.asList("1", "2", "3");
+        List<String> otherLights = List.of("1", "2", "3");
 
         Scene scene = new Scene(PLACEHOLDER, PLACEHOLDER, groupId, lights, false);
 
@@ -76,8 +75,8 @@ public class SceneTest {
      */
     @Test
     public void testIsApplicableToNoGroupIdSceneLightsContainedInGroup() {
-        List<String> lights = Arrays.asList("1", "2");
+        List<String> lights = List.of("1", "2");
-        List<String> moreLights = Arrays.asList("1", "2", "3");
+        List<String> moreLights = List.of("1", "2", "3");
 
         Scene scene = new Scene(PLACEHOLDER, PLACEHOLDER, null, lights, false);
 
@@ -96,9 +95,9 @@ public class SceneTest {
      */
     @Test
     public void testIsApplicableToNoGroupIdSceneLightsNotContainedInGroup() {
-        List<String> lights = Arrays.asList("1", "2");
+        List<String> lights = List.of("1", "2");
-        List<String> lessLights = Arrays.asList("1");
+        List<String> lessLights = List.of("1");
-        List<String> differentLights = Arrays.asList("3");
+        List<String> differentLights = List.of("3");
 
         Scene scene = new Scene(PLACEHOLDER, PLACEHOLDER, null, lights, false);
 

itests/org.openhab.binding.hue.tests/src/main/java/org/openhab/binding/hue/internal/AbstractHueOSGiTestParent.java

@@ -14,13 +14,16 @@ package org.openhab.binding.hue.internal;
 
 import static org.junit.jupiter.api.Assertions.*;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
 import org.openhab.core.test.java.JavaOSGiTest;
 import org.openhab.core.thing.Thing;
 import org.openhab.core.thing.binding.ThingHandler;
 
 /**
+ * @author Markus Rathgeb - Initial contribution
  * @author Markus Rathgeb - migrated to plain Java test
  */
+@NonNullByDefault
 public class AbstractHueOSGiTestParent extends JavaOSGiTest {
 
     /**
@@ -38,7 +41,7 @@ public class AbstractHueOSGiTestParent extends JavaOSGiTest {
             } else {
                 assertNotNull(tmp);
                 assertEquals(clazz, tmp.getClass());
-                throw new RuntimeException();
+                throw new IllegalStateException();
             }
         });
     }

itests/org.openhab.binding.hue.tests/src/main/java/org/openhab/binding/hue/internal/HueDeviceDiscoveryServiceOSGiTest.java

@@ -25,6 +25,8 @@ import java.util.concurrent.Executors;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.atomic.AtomicReference;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.jdt.annotation.Nullable;
 import org.eclipse.jetty.client.HttpClient;
 import org.eclipse.jetty.http.HttpStatus;
 import org.junit.jupiter.api.AfterEach;
@@ -61,16 +63,17 @@ import org.openhab.core.thing.binding.builder.ThingStatusInfoBuilder;
  * @author Denis Dudnik - switched to internally integrated source of Jue library
  * @author Markus Rathgeb - migrated to plain Java test
  */
+@NonNullByDefault
 public class HueDeviceDiscoveryServiceOSGiTest extends AbstractHueOSGiTestParent {
 
-    protected DiscoveryListener discoveryListener;
+    protected @Nullable DiscoveryListener discoveryListener;
-    protected ThingRegistry thingRegistry;
+    protected @NonNullByDefault({}) ThingRegistry thingRegistry;
-    protected Bridge hueBridge;
+    protected @NonNullByDefault({}) Bridge hueBridge;
-    protected HueBridgeHandler hueBridgeHandler;
+    protected @NonNullByDefault({}) HueBridgeHandler hueBridgeHandler;
-    protected HueDeviceDiscoveryService discoveryService;
+    protected @NonNullByDefault({}) HueDeviceDiscoveryService discoveryService;
 
-    protected final ThingTypeUID BRIDGE_THING_TYPE_UID = new ThingTypeUID("hue", "bridge");
+    protected static final ThingTypeUID BRIDGE_THING_TYPE_UID = new ThingTypeUID("hue", "bridge");
-    protected final ThingUID BRIDGE_THING_UID = new ThingUID(BRIDGE_THING_TYPE_UID, "testBridge");
+    protected static final ThingUID BRIDGE_THING_UID = new ThingUID(BRIDGE_THING_TYPE_UID, "testBridge");
 
     @BeforeEach
     public void setUp() {
@@ -139,8 +142,8 @@ public class HueDeviceDiscoveryServiceOSGiTest extends AbstractHueOSGiTestParent
             }
 
             @Override
-            public Collection<ThingUID> removeOlderResults(DiscoveryService source, long timestamp,
+            public @Nullable Collection<ThingUID> removeOlderResults(DiscoveryService source, long timestamp,
-                    Collection<ThingTypeUID> thingTypeUIDs, ThingUID bridgeUID) {
+                    @Nullable Collection<ThingTypeUID> thingTypeUIDs, @Nullable ThingUID bridgeUID) {
                 return null;
             }
         });

itests/org.openhab.binding.hue.tests/src/main/java/org/openhab/binding/hue/internal/discovery/HueBridgeNupnpDiscoveryOSGITest.java

@@ -26,7 +26,8 @@ import java.util.List;
 import java.util.Map;
 import java.util.stream.Collectors;
 
-import org.eclipse.jdt.annotation.NonNull;
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.jdt.annotation.Nullable;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 import org.openhab.core.config.discovery.DiscoveryListener;
@@ -43,26 +44,31 @@ import org.openhab.core.thing.ThingUID;
  * @author Christoph Knauf - Initial contribution
  * @author Markus Rathgeb - migrated to plain Java test
  */
+@NonNullByDefault
 public class HueBridgeNupnpDiscoveryOSGITest extends JavaOSGiTest {
 
-    HueBridgeNupnpDiscovery sut;
+    private @NonNullByDefault({}) HueBridgeNupnpDiscovery sut;
-    VolatileStorageService volatileStorageService = new VolatileStorageService();
+    private VolatileStorageService volatileStorageService = new VolatileStorageService();
-    DiscoveryListener discoveryListener;
+    private @Nullable DiscoveryListener discoveryListener;
-    Inbox inbox;
+    private @NonNullByDefault({}) Inbox inbox;
 
-    final ThingTypeUID BRIDGE_THING_TYPE_UID = new ThingTypeUID("hue", "bridge");
+    private static final ThingTypeUID BRIDGE_THING_TYPE_UID = new ThingTypeUID("hue", "bridge");
-    final String ip1 = "192.168.31.17";
+    private static final String IP1 = "192.168.31.17";
-    final String ip2 = "192.168.30.28";
+    private static final String IP2 = "192.168.30.28";
-    final String sn1 = "001788fffe20057f";
+    private static final String SN1 = "001788fffe20057f";
-    final String sn2 = "001788fffe141b41";
+    private static final String SN2 = "001788fffe141b41";
-    final ThingUID BRIDGE_THING_UID_1 = new ThingUID(BRIDGE_THING_TYPE_UID, sn1);
+    private static final ThingUID BRIDGE_THING_UID_1 = new ThingUID(BRIDGE_THING_TYPE_UID, SN1);
-    final ThingUID BRIDGE_THING_UID_2 = new ThingUID(BRIDGE_THING_TYPE_UID, sn2);
+    private static final ThingUID BRIDGE_THING_UID_2 = new ThingUID(BRIDGE_THING_TYPE_UID, SN2);
-    final String validBridgeDiscoveryResult = "[{\"id\":\"" + sn1 + "\",\"internalipaddress\":" + ip1 + "},{\"id\":\""
-            + sn2 + "\",\"internalipaddress\":" + ip2 + "}]";
-    String discoveryResult;
-    String expBridgeDescription = "{\"name\":\"Philips hue\",\"datastoreversion\":\"149\",\"swversion\":\"1957113050\",\"apiversion\":\"1.57.0\",\"mac\":\"00:11:22:33:44\",\"bridgeid\":\"$SN\",\"factorynew\":false,\"replacesbridgeid\":null,\"modelid\":\"BSB002\",\"starterkitid\":\"\"}";
 
-    private void checkDiscoveryResult(DiscoveryResult result, String expIp, String expSn) {
+    private final String validBridgeDiscoveryResult = "[{\"id\":\"" + SN1 + "\",\"internalipaddress\":" + IP1
+            + "},{\"id\":\"" + SN2 + "\",\"internalipaddress\":" + IP2 + "}]";
+    private @Nullable String discoveryResult;
+    private String expBridgeDescription = "{\"name\":\"Philips hue\",\"datastoreversion\":\"149\",\"swversion\":\"1957113050\",\"apiversion\":\"1.57.0\",\"mac\":\"00:11:22:33:44\",\"bridgeid\":\"$SN\",\"factorynew\":false,\"replacesbridgeid\":null,\"modelid\":\"BSB002\",\"starterkitid\":\"\"}";
+
+    private void checkDiscoveryResult(@Nullable DiscoveryResult result, String expIp, String expSn) {
+        if (result == null) {
+            return;
+        }
         assertThat(result.getBridgeUID(), nullValue());
         assertThat(result.getLabel(), is(String.format(DISCOVERY_LABEL_PATTERN, expIp)));
         assertThat(result.getProperties().get("ipAddress"), is(expIp));
@@ -88,19 +94,19 @@ public class HueBridgeNupnpDiscoveryOSGITest extends JavaOSGiTest {
         }
 
         @Override
-        protected String doGetRequest(String url) throws IOException {
+        protected @Nullable String doGetRequest(String url) throws IOException {
             if (url.contains("meethue")) {
                 return discoveryResult;
-            } else if (url.contains(ip1)) {
+            } else if (url.contains(IP1)) {
-                return expBridgeDescription.replaceAll("$SN", sn1);
+                return expBridgeDescription.replaceAll("$SN", SN1);
-            } else if (url.contains(ip2)) {
+            } else if (url.contains(IP2)) {
-                return expBridgeDescription.replaceAll("$SN", sn2);
+                return expBridgeDescription.replaceAll("$SN", SN2);
             }
             throw new IOException();
         }
 
         @Override
-        protected boolean isClip2Supported(@NonNull String ipAddress) {
+        protected boolean isClip2Supported(String ipAddress) {
             return false;
         }
     }
@@ -147,8 +153,8 @@ public class HueBridgeNupnpDiscoveryOSGITest extends JavaOSGiTest {
             }
 
             @Override
-            public Collection<ThingUID> removeOlderResults(DiscoveryService source, long timestamp,
+            public @Nullable Collection<ThingUID> removeOlderResults(DiscoveryService source, long timestamp,
-                    Collection<ThingTypeUID> thingTypeUIDs, ThingUID bridgeUID) {
+                    @Nullable Collection<ThingTypeUID> thingTypeUIDs, @Nullable ThingUID bridgeUID) {
                 return null;
             }
         });
@@ -158,9 +164,9 @@ public class HueBridgeNupnpDiscoveryOSGITest extends JavaOSGiTest {
         waitForAssert(() -> {
             assertThat(results.size(), is(2));
             assertThat(results.get(BRIDGE_THING_UID_1), is(notNullValue()));
-            checkDiscoveryResult(results.get(BRIDGE_THING_UID_1), ip1, sn1);
+            checkDiscoveryResult(results.get(BRIDGE_THING_UID_1), IP1, SN1);
             assertThat(results.get(BRIDGE_THING_UID_2), is(notNullValue()));
-            checkDiscoveryResult(results.get(BRIDGE_THING_UID_2), ip2, sn2);
+            checkDiscoveryResult(results.get(BRIDGE_THING_UID_2), IP2, SN2);
 
             final List<DiscoveryResult> inboxResults = inbox.stream().filter(forThingTypeUID(BRIDGE_THING_TYPE_UID))
                     .collect(Collectors.toList());
@@ -195,8 +201,8 @@ public class HueBridgeNupnpDiscoveryOSGITest extends JavaOSGiTest {
             }
 
             @Override
-            public Collection<ThingUID> removeOlderResults(DiscoveryService source, long timestamp,
+            public @Nullable Collection<ThingUID> removeOlderResults(DiscoveryService source, long timestamp,
-                    Collection<ThingTypeUID> thingTypeUIDs, ThingUID bridgeUID) {
+                    @Nullable Collection<ThingTypeUID> thingTypeUIDs, @Nullable ThingUID bridgeUID) {
                 return null;
             }
         });
@@ -254,7 +260,7 @@ public class HueBridgeNupnpDiscoveryOSGITest extends JavaOSGiTest {
 
         // invalid bridge description
         expBridgeDescription = "";
-        discoveryResult = "[{\"id\":\"001788fffe20057f\",\"internalipaddress\":" + ip1 + "}]";
+        discoveryResult = "[{\"id\":\"001788fffe20057f\",\"internalipaddress\":" + IP1 + "}]";
         sut.startScan();
         waitForAssert(() -> {
             assertThat(results.size(), is(0));

itests/org.openhab.binding.hue.tests/src/main/java/org/openhab/binding/hue/internal/handler/HueBridgeHandlerOSGiTest.java

@@ -23,6 +23,7 @@ import java.io.IOException;
 import java.lang.reflect.Field;
 import java.util.concurrent.ScheduledExecutorService;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
 import org.eclipse.jetty.client.HttpClient;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
@@ -50,15 +51,15 @@ import org.openhab.core.thing.ThingUID;
  * @author Michael Grammling - Initial contribution
  * @author Denis Dudnik - switched to internally integrated source of Jue library
  */
+@NonNullByDefault
 public class HueBridgeHandlerOSGiTest extends AbstractHueOSGiTestParent {
 
     private static final ThingTypeUID BRIDGE_THING_TYPE_UID = new ThingTypeUID(BINDING_ID, "bridge");
     private static final String TEST_USER_NAME = "eshTestUser";
     private static final String DUMMY_HOST = "1.2.3.4";
 
-    private ThingRegistry thingRegistry;
+    private @NonNullByDefault({}) ThingRegistry thingRegistry;
-
+    private @NonNullByDefault({}) ScheduledExecutorService scheduler;
-    private ScheduledExecutorService scheduler;
 
     @BeforeEach
     public void setUp() {