Add support for FilterMaintenanceAccessory

[#124](#124)

Author: gjvanderheiden

CHANGES.md

@@ -13,6 +13,7 @@
 
 * Valid values are supported for enum characteristics instead of min and max values
 * Supported valid states for Thermostat, SecuritySystem, HeaterCooler and HumidifierDehumidifier [#108] [#120](https://github.com/hap-java/HAP-Java/pull/120)
+* Support for FilterMaintenance. Can be used as a linked service for a Air Purifier  [#124](https://github.com/hap-java/HAP-Java/pull/124)
 
 # HAP-Java 1.1.5
 

README.md

@@ -23,7 +23,7 @@ After that, check out the [Sample](https://github.com/hap-java/HAP-Java/tree/sam
 Supported HomeKit Accessories
 =========
 
-Current implementation fully supports 37 HomeKit accessory/services.
+Current implementation fully supports 38 HomeKit accessory/services.
 
 | HomeKit Accessory & Service type | Supported by Java-HAP |
 |--------------------|--------------------|
@@ -41,7 +41,7 @@ Current implementation fully supports 37 HomeKit accessory/services.
 |  Doorbell                         |     :white_check_mark:    |
 |  Fan                              |     :white_check_mark:    |
 |  Faucet                           |     :white_check_mark:    |
-|  Filter Maintenance               |     :x:                   |
+|  Filter Maintenance               |     :white_check_mark:    |
 |  Garage Door Opener               |     :white_check_mark:    |
 |  HAP Protocol Information         |     :white_check_mark:    |
 |  Heater Cooler                    |     :white_check_mark:    |

src/main/java/io/github/hapjava/accessories/AirPurifierAccessory.java

@@ -79,8 +79,23 @@ public interface AirPurifierAccessory extends HomekitAccessory {
   /** Unsubscribes from changes in the target state of the air purifier. */
   void unsubscribeTargetState();
 
+  /**
+   * If a filter maintenance service is needed as a linked service to this AirPurifier, this is the
+   * place.
+   *
+   * @return an instance of FilterMaintenanceAccessory, null if not needed.
+   */
+  default FilterMaintenanceAccessory getFilterMaintenanceAccessory() {
+    return null;
+  };
+
   @Override
   default Collection<Service> getServices() {
-    return Collections.singleton(new AirPurifierService(this));
+    AirPurifierService service = new AirPurifierService(this);
+    FilterMaintenanceAccessory fmAccessory = this.getFilterMaintenanceAccessory();
+    if (fmAccessory != null) {
+      service.addLinkedService(fmAccessory.getPrimaryService());
+    }
+    return Collections.singleton(service);
   }
 }

src/main/java/io/github/hapjava/characteristics/impl/base/IntegerCharacteristic.java

@@ -62,17 +62,21 @@ protected CompletableFuture<JsonObjectBuilder> makeBuilder(int iid) {
     return super.makeBuilder(iid)
         .thenApply(
             builder -> {
-              return builder
-                  .add("minValue", minValue)
-                  .add("maxValue", maxValue)
-                  .add("minStep", 1)
-                  .add("unit", unit);
+              builder.add("minValue", minValue).add("maxValue", maxValue).add("minStep", 1);
+              if (this.unit != null) {
+                builder.add("unit", unit);
+              }
+              return builder;
             });
   }
 
   @Override
   protected CompletableFuture<Integer> getValue() {
-    return getter.map(integerGetter -> integerGetter.get()).get();
+    if (getter.isPresent()) {
+      return getter.map(integerGetter -> integerGetter.get()).get();
+    } else {
+      return null;
+    }
   }
 
   @Override

src/main/java/io/github/hapjava/services/impl/AirPurifierService.java

@@ -3,6 +3,7 @@
 import io.github.hapjava.accessories.AirPurifierAccessory;
 import io.github.hapjava.accessories.optionalcharacteristic.AccessoryWithName;
 import io.github.hapjava.accessories.optionalcharacteristic.AccessoryWithPhysicalControlsLock;
+import io.github.hapjava.accessories.optionalcharacteristic.AccessoryWithRotationSpeed;
 import io.github.hapjava.accessories.optionalcharacteristic.AccessoryWithSwingMode;
 import io.github.hapjava.characteristics.impl.airpurifier.CurrentAirPurifierCharacteristic;
 import io.github.hapjava.characteristics.impl.airpurifier.TargetAirPurifierStateCharacteristic;
@@ -53,13 +54,13 @@ public AirPurifierService(AirPurifierAccessory accessory) {
               ((AccessoryWithSwingMode) accessory)::subscribeSwingMode,
               ((AccessoryWithSwingMode) accessory)::unsubscribeSwingMode));
     }
-    if (accessory instanceof AccessoryWithSwingMode) {
+    if (accessory instanceof AccessoryWithRotationSpeed) {
       addOptionalCharacteristic(
-          new SwingModeCharacteristic(
-              ((AccessoryWithSwingMode) accessory)::getSwingMode,
-              ((AccessoryWithSwingMode) accessory)::setSwingMode,
-              ((AccessoryWithSwingMode) accessory)::subscribeSwingMode,
-              ((AccessoryWithSwingMode) accessory)::unsubscribeSwingMode));
+          new RotationSpeedCharacteristic(
+              ((AccessoryWithRotationSpeed) accessory)::getRotationSpeed,
+              ((AccessoryWithRotationSpeed) accessory)::setRotationSpeed,
+              ((AccessoryWithRotationSpeed) accessory)::subscribeRotationSpeed,
+              ((AccessoryWithRotationSpeed) accessory)::unsubscribeRotationSpeed));
     }
     if (accessory instanceof AccessoryWithPhysicalControlsLock) {
       addOptionalCharacteristic(