Fixes #696

exercises/series/src/test/java/SeriesTest.java

 import java.util.Arrays;
+import java.util.Collections;
 import java.util.List;
 
 import org.junit.Test;
     public void canSliceByOne() {
         Series series = new Series("01234");
         List<List<Integer>> expected = Arrays.asList(
-                Arrays.asList(0),
-                Arrays.asList(1),
-                Arrays.asList(2),
-                Arrays.asList(3),
-                Arrays.asList(4)
+		        Collections.singletonList(0),
+                Collections.singletonList(1),
+                Collections.singletonList(2),
+                Collections.singletonList(3),
+                Collections.singletonList(4)
         );
         List<List<Integer>> actual = series.slices(1);
         assertNotNull(actual);