=str: various minor cleanups

akka-stream-tests/src/test/java/akka/stream/javadsl/AttributesTest.java

@@ -5,6 +5,8 @@ package akka.stream.javadsl;
 
 import static org.junit.Assert.assertEquals;
 import java.util.Arrays;
+import java.util.Collections;
+
 import org.junit.Test;
 
 import akka.stream.Attributes;
@@ -22,7 +24,7 @@ public class AttributesTest {
       Arrays.asList(new Attributes.Name("a"), new Attributes.Name("b")),
       attributes.getAttributeList(Attributes.Name.class));
     assertEquals(
-        Arrays.asList(new Attributes.InputBuffer(1, 2)),
+        Collections.singletonList(new Attributes.InputBuffer(1, 2)),
         attributes.getAttributeList(Attributes.InputBuffer.class));
   }