This is a copy of the following PR dariuszseweryn#112

It allows users to request a certain priority for each connection.

mockrxandroidble/src/main/java/com/polidea/rxandroidble/mockrxandroidble/RxBleConnectionMock.java

@@ -47,6 +47,11 @@ public Observable<RxBleDeviceServices> discoverServices() {
         return Observable.just(rxBleDeviceServices);
     }
 
+    @Override
+    public void requestConnectionPriority(int priority) {
+
+    }
+
     @Override
     public Observable<RxBleDeviceServices> discoverServices(long timeout, TimeUnit timeUnit) {
         return Observable.just(rxBleDeviceServices);

rxandroidble/src/main/java/com/polidea/rxandroidble/RxBleConnection.java

@@ -48,6 +48,9 @@ public String toString() {
         }
     }
 
+    @RequiresApi(api = Build.VERSION_CODES.LOLLIPOP)
+    void requestConnectionPriority(int priority);
+
     /**
      * Performs GATT service discovery and emits discovered results. After service discovery you can walk through
      * {@link android.bluetooth.BluetoothGattService}s and {@link BluetoothGattCharacteristic}s.

rxandroidble/src/main/java/com/polidea/rxandroidble/internal/connection/RxBleConnectionImpl.java

@@ -81,6 +81,12 @@ private Observable<Integer> privateRequestMtu(int mtu, long timeout, TimeUnit ti
         return newObservable;
     }
 
+    @RequiresApi(api = Build.VERSION_CODES.LOLLIPOP)
+    @Override
+    public void requestConnectionPriority(int priority) {
+        bluetoothGatt.requestConnectionPriority(priority);
+    }
+
     @Override
     public Observable<RxBleDeviceServices> discoverServices() {
         return privateDiscoverServices(20, TimeUnit.SECONDS);