Readability improvements XmppPeerRepository

data/src/main/java/org/mercury_im/messenger/data/repository/XmppPeerRepository.java

@@ -24,6 +24,9 @@ import io.reactivex.Observable;
 import io.reactivex.Scheduler;
 import io.reactivex.Single;
 import io.requery.Persistable;
+import io.requery.query.Conditional;
+import io.requery.query.Expression;
+import io.requery.query.LogicalCondition;
 import io.requery.query.ResultDelegate;
 import io.requery.reactivex.ReactiveEntityStore;
 
@@ -139,8 +142,7 @@ public class XmppPeerRepository
     public Observable<List<Peer>> observeAllContactsOfAccount(UUID accountId) {
         return data().select(PeerModel.class)
                 .where(PeerModel.ACCOUNT_ID.eq(accountId))
-                .and(PeerModel.SUBSCRIPTION_DIRECTION.in(
-                        Arrays.asList(SubscriptionDirection.both, SubscriptionDirection.to)))
+                .and(isContact())
                 .get().observableResult()
                 .map(ResultDelegate::toList)
                 .map(peerModels -> {
@@ -154,6 +156,12 @@ public class XmppPeerRepository
                 .observeOn(observerScheduler());
     }
 
+    private LogicalCondition<? extends Expression<SubscriptionDirection>, ?> isContact() {
+        return PeerModel.SUBSCRIPTION_DIRECTION.in(Arrays.asList(
+                SubscriptionDirection.both,
+                SubscriptionDirection.to));
+    }
+
     @Override
     public Single<Peer> updatePeer(Peer peer) {
         // In order to update, we fetch the model, update it and write it back.