Imported Upstream version 3.6.0

Former-commit-id: da6be194a6b1221998fc28233f2503bd61dd9d14

mcs/class/System.IO.Compression/SharpCompress/ReadOnlyCollection.cs

@@ -0,0 +1,60 @@
+using System;
+using System.Collections.Generic;
+
+namespace SharpCompress
+{
+    internal class ReadOnlyCollection<T> : ICollection<T>
+    {
+        private ICollection<T> collection;
+
+        public ReadOnlyCollection(ICollection<T> collection)
+        {
+            this.collection = collection;
+        }
+
+        public void Add(T item)
+        {
+            throw new NotImplementedException();
+        }
+
+        public void Clear()
+        {
+            throw new NotImplementedException();
+        }
+
+        public bool Contains(T item)
+        {
+            return collection.Contains(item);
+        }
+
+        public void CopyTo(T[] array, int arrayIndex)
+        {
+            collection.CopyTo(array, arrayIndex);
+        }
+
+        public int Count
+        {
+            get { return collection.Count; }
+        }
+
+        public bool IsReadOnly
+        {
+            get { return true; }
+        }
+
+        public bool Remove(T item)
+        {
+            throw new NotImplementedException();
+        }
+
+        public IEnumerator<T> GetEnumerator()
+        {
+            return collection.GetEnumerator();
+        }
+
+        System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator()
+        {
+            throw new NotImplementedException();
+        }
+    }
+}