Add better iterator over java iterable

core/src/main/csharp/java/lang/IterableExtensions.cs

@@ -0,0 +1,37 @@
+using java.util;
+using System;
+using System.Collections;
+
+namespace java.lang
+{
+    public static class IterableExtensions
+    {
+        public static IterableEnumerator GetEnumerator(this Iterable iterable) => new(iterable);
+
+        public struct IterableEnumerator : IEnumerator
+        {
+            private object current;
+            private Iterator iterator;
+
+            public IterableEnumerator(Iterable list)
+            {
+                iterator = list.iterator();
+                current = default;
+            }
+
+            public object Current => current;
+
+            public bool MoveNext()
+            {
+                if (iterator.hasNext())
+                {
+                    current = iterator.next();
+                    return true;
+                }
+                return false;
+            }
+
+            public void Reset() => throw new NotImplementedException();
+        }
+    }
+}

core/src/main/csharp/java/util/CollectionExtensions.cs

@@ -0,0 +1,9 @@
+using java.lang;
+
+namespace java.util
+{
+    public static class CollectionExtensions
+    {
+        public static IterableExtensions.IterableEnumerator GetEnumerator(this Collection collection) => ((Iterable)collection).GetEnumerator();
+    }
+}