Query: allow comparator for findUnique()

Author: greenrobot

objectbox-java/src/main/java/io/objectbox/query/Query.java

@@ -182,7 +182,7 @@ private void ensureNoComparator() {
      */
     @Nullable
     public T findUnique() {
-        ensureNoFilterNoComparator();
+        ensureNoFilter();  // Comparator is fine: does not make any difference for a unique result
         return callInReadTx(new Callable<T>() {
             @Override
             public T call() {

tests/objectbox-java-test/src/test/java/io/objectbox/query/QueryFilterComparatorTest.java

@@ -144,8 +144,8 @@ public void comparator_findFirst_unsupported() {
                 .findFirst();
     }
 
-    @Test(expected = UnsupportedOperationException.class)
-    public void comparator_findUnique_unsupported() {
+    @Test
+    public void comparator_findUnique_supported() {
         box.query()
                 .sort(createTestComparator())
                 .build()