Found one more unsupported case in iterators. Add link to task in JavaDoc

Author: andrei-punko

src/main/java/by/andd3dfx/iterators/NestedIterator.java

@@ -8,6 +8,8 @@
 
 /**
  * <pre>
+ * <a href="https://leetcode.com/problems/flatten-nested-list-iterator/description/">Task description</a>
+ *
  * You are given a nested list of integers nestedList. Each element is either an integer or a list whose elements may also be integers or other lists. Implement an iterator to flatten it.
  *
  * Implement the NestedIterator class:

src/test/java/by/andd3dfx/iterators/RecursiveIteratorTest.java

@@ -1,5 +1,6 @@
 package by.andd3dfx.iterators;
 
+import org.junit.Ignore;
 import org.junit.Test;
 
 import java.util.ArrayList;
@@ -41,6 +42,20 @@ public void testNextHasNextForComplexStructure() {
         assertThat(result).isEqualTo(List.of("1", "3", "9", "4", "23", "31", "88", "22", "5", "37", "11"));
     }
 
+    @Ignore("TODO: change implemetation to support this case")
+    @Test
+    public void testNextForListOfEmptyLists() {
+        List<Object> list = Arrays.asList(List.of(), List.of(List.of()));
+        var iterator = new RecursiveIterator<>(list.iterator());
+
+        List<String> result = new ArrayList<>();
+        while (iterator.hasNext()) {
+            result.add((String) iterator.next());
+        }
+
+        assertThat(result).isEqualTo(List.of());
+    }
+
     @Test(expected = NoSuchElementException.class)
     public void callNextAfterEndOfIterator() {
         List<String> list = Arrays.asList("1", "3", "5", "7", "9");