OAK-11565 : added util to replace Iterables.get in oak-commons (#2158)

* OAK-11565 : added util to replace Iterables.get in oak-commons

* Update oak-commons/src/main/java/org/apache/jackrabbit/oak/commons/collections/IterableUtils.java

Co-authored-by: Julian Reschke <reschke@apache.org>

---------

Co-authored-by: Rishabh Kumar <diam@adobe.com>
Co-authored-by: Julian Reschke <reschke@apache.org>

Author: 3 people

oak-commons/src/main/java/org/apache/jackrabbit/oak/commons/collections/IterableUtils.java

@@ -408,4 +408,24 @@ public static <T> T getFirst(final Iterable<T> iterable, final  T defaultValue)
         final Iterator<T> iterator = iterable.iterator();
         return iterator.hasNext() ? iterator.next() : defaultValue;
     }
+
+    /**
+     * Returns the element at the specified index in the specified iterable.
+     * <p>
+     * The iterable is traversed until the specified index is reached. If the
+     * position is greater than the number of elements in the iterable, an
+     * IndexOutOfBoundsException is thrown.
+     *
+     * @param <T> the type of elements in the iterable
+     * @param iterable the iterable to get the element from, must not be null
+     * @param index the index of the element to retrieve, must be non-negative
+     * @return the element at the specified index
+     * @throws NullPointerException if the iterable is null
+     * @throws IndexOutOfBoundsException if the position is negative or greater than
+     *         the number of elements in the iterable
+     */
+    public static <T> T get(final Iterable<T> iterable, final int index) {
+        Objects.requireNonNull(iterable, "Iterable must not be null.");
+        return org.apache.commons.collections4.IterableUtils.get(iterable, index);
+    }
 }

oak-commons/src/test/java/org/apache/jackrabbit/oak/commons/collections/IterableUtilsTest.java

@@ -910,4 +910,63 @@ public void testGetFirstWithCustomIterable() {
         Integer result = IterableUtils.getFirst(customIterable, 0);
         Assert.assertEquals(Integer.valueOf(5), result);
     }
+
+    @Test
+    public void testGetWithValidPosition() {
+        List<String> list = Arrays.asList("a", "b", "c", "d", "e");
+        String result = IterableUtils.get(list, 2);
+        Assert.assertEquals("c", result);
+    }
+
+    @Test
+    public void testGetFirstElement() {
+        List<String> list = Arrays.asList("a", "b", "c");
+        String result = IterableUtils.get(list, 0);
+        Assert.assertEquals("a", result);
+    }
+
+    @Test
+    public void testGetLastElement() {
+        List<String> list = Arrays.asList("a", "b", "c");
+        String result = IterableUtils.get(list, 2);
+        Assert.assertEquals("c", result);
+    }
+
+    @Test(expected = IndexOutOfBoundsException.class)
+    public void testGetWithNegativePosition() {
+        List<String> list = Arrays.asList("a", "b", "c");
+        IterableUtils.get(list, -1);
+    }
+
+    @Test(expected = IndexOutOfBoundsException.class)
+    public void testGetWithPositionTooLarge() {
+        List<String> list = Arrays.asList("a", "b", "c");
+        IterableUtils.get(list, 3);
+    }
+
+    @Test(expected = IndexOutOfBoundsException.class)
+    public void testGetWithEmptyIterable() {
+        List<String> list = Collections.emptyList();
+        IterableUtils.get(list, 0);
+    }
+
+    @Test(expected = NullPointerException.class)
+    public void testGetWithNullIterable() {
+        IterableUtils.get(null, 0);
+    }
+
+    @Test
+    public void testGetWithCustomIterable() {
+        // Custom iterable implementation
+        Iterable<Integer> customIterable = () -> Arrays.asList(5, 10, 15, 20, 25).iterator();
+        Integer result = IterableUtils.get(customIterable, 3);
+        Assert.assertEquals(Integer.valueOf(20), result);
+    }
+
+    @Test
+    public void testGetWithSingleElementIterable() {
+        List<String> list = Collections.singletonList("only");
+        String result = IterableUtils.get(list, 0);
+        Assert.assertEquals("only", result);
+    }
 }