diff --git a/euphoria-core/src/main/java/cz/seznam/euphoria/core/client/operator/ReduceByKey.java b/euphoria-core/src/main/java/cz/seznam/euphoria/core/client/operator/ReduceByKey.java
index 01e9f2b6..a74f28b1 100644
--- a/euphoria-core/src/main/java/cz/seznam/euphoria/core/client/operator/ReduceByKey.java
+++ b/euphoria-core/src/main/java/cz/seznam/euphoria/core/client/operator/ReduceByKey.java
@@ -348,7 +348,7 @@ public static class DatasetBuilder5<IN, KEY, VALUE, OUT, W extends Window>
     public Dataset<Pair<KEY, OUT>> output(OutputHint... outputHints) {
       Flow flow = input.getFlow();
       ReduceByKey<IN, KEY, VALUE, OUT, W> reduce = new ReduceByKey<>(
-              name, flow, input, keyExtractor, valueExtractor,
+          name, flow, input, keyExtractor, valueExtractor,
           windowing, reducer, valuesComparator, Sets.newHashSet(outputHints));
       flow.add(reduce);
       return reduce.output();
diff --git a/euphoria-core/src/test/java/cz/seznam/euphoria/core/client/operator/JoinTest.java b/euphoria-core/src/test/java/cz/seznam/euphoria/core/client/operator/JoinTest.java
index c19880aa..0c5fbea3 100644
--- a/euphoria-core/src/test/java/cz/seznam/euphoria/core/client/operator/JoinTest.java
+++ b/euphoria-core/src/test/java/cz/seznam/euphoria/core/client/operator/JoinTest.java
@@ -198,7 +198,6 @@ public void testBuild_Windowing() {
     assertTrue(join.getWindowing() instanceof Time);
   }
 
-
   @Test
   @SuppressWarnings("unchecked")
   public void testBuild_Hints() {
@@ -218,12 +217,27 @@ public void testBuild_Hints() {
 
     assertTrue(outputDataset.getProducer().getHints().contains(SizeHint.FITS_IN_MEMORY));
 
-    Join join = (Join) flow.operators().stream().filter(op -> op instanceof Join).findFirst().get();
-    assertTrue(join.listInputs().stream().anyMatch(input ->
-        ((Dataset) input).getProducer().getHints().contains(new Util.TestHint())));
-    assertTrue(join.listInputs().stream().anyMatch(input -> 
-        ((Dataset) input).getProducer().getHints().contains(new Util.TestHint2())));
-    assertEquals(2, ((Dataset) join.listInputs().stream().findFirst().get()).getProducer().getHints().size());
+    Join join = (Join) flow.operators()
+        .stream()
+        .filter(op -> op instanceof Join)
+        .findFirst()
+        .get();
+    assertTrue(join.listInputs()
+        .stream()
+        .anyMatch(input ->
+            ((Dataset) input).getProducer().getHints().contains(new Util.TestHint())));
+
+    assertTrue(join.listInputs()
+        .stream()
+        .anyMatch(input ->
+            ((Dataset) input).getProducer().getHints().contains(new Util.TestHint2())));
+
+    assertEquals(2,
+        ((Dataset) join.listInputs()
+            .stream()
+            .findFirst()
+            .get()
+        ).getProducer().getHints().size());
 
   }
 
@@ -235,7 +249,9 @@ public void testBuild_Hints_afterWindowing() {
     Dataset<String> right = Util.createMockDataset(flow, 1);
 
     Join.named("Join1")
-        .of(MapElements.of(left).using(i -> i).output(new Util.TestHint(), new Util.TestHint2(), new Util.TestHint2()),
+        .of(MapElements.of(left)
+                .using(i -> i)
+                .output(new Util.TestHint(), new Util.TestHint2(), new Util.TestHint2()),
             right)
         .by(String::length, String::length)
         .using((String l, String r, Collector<String> c) -> {
@@ -244,12 +260,31 @@ public void testBuild_Hints_afterWindowing() {
         .windowBy(Time.of(Duration.ofHours(1)))
         .output();
 
-    Join join = (Join) flow.operators().stream().filter(op -> op instanceof Join).findFirst().get();
-    assertTrue(join.listInputs().stream().anyMatch(input ->
-        ((Dataset)input).getProducer().getHints().contains(new Util.TestHint())));
-    assertTrue(join.listInputs().stream().anyMatch(input ->
-        ((Dataset)input).getProducer().getHints().contains(new Util.TestHint2())));
-    assertEquals(2, ((Dataset) join.listInputs().stream().findFirst().get()).getProducer().getHints().size());
+    Join join = (Join) flow.operators()
+        .stream()
+        .filter(op -> op instanceof Join)
+        .findFirst()
+        .get();
+    assertTrue(join.listInputs()
+        .stream()
+        .anyMatch(input ->
+            ((Dataset) input).getProducer().getHints().contains(new Util.TestHint())));
+
+    assertTrue(join.listInputs()
+        .stream()
+        .anyMatch(input ->
+            ((Dataset) input)
+                .getProducer()
+                .getHints()
+                .contains(new Util.TestHint2())));
+
+    assertEquals(2,
+        ((Dataset) join.listInputs()
+            .stream()
+            .findFirst()
+            .get()
+        ).getProducer().getHints().size());
+
     assertTrue(join.getWindowing() instanceof Time);
   }
 }
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