Fix issue with concurrent logging (#63)

* Fix issue with concurrent logging

* Fix namespace + code format/cleanup

src/WireMock.Net/Util/ConcurentObservableCollection.cs

@@ -0,0 +1,77 @@
+using System.Collections.Generic;
+using System.Collections.ObjectModel;
+
+namespace WireMock.Util
+{
+    /// <summary>
+    /// A special Collection that overrides methods of <see cref="ObservableCollection{T}"/> to make them thread safe
+    /// </summary>
+    /// <typeparam name="T">The type of elements in the collection.</typeparam>
+    /// <inheritdoc cref="ObservableCollection{T}" />
+    public class ConcurentObservableCollection<T> : ObservableCollection<T>
+    {
+        private readonly object _lockObject = new object();
+
+        /// <summary> 
+        /// Initializes a new instance of the <see cref="T:WireMock.Util.ConcurentObservableCollection`1" /> class. 
+        /// </summary> 
+        public ConcurentObservableCollection() { }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="ConcurentObservableCollection{T}"/> class that contains elements copied from the specified list.
+        /// </summary>
+        /// <param name="list">The list from which the elements are copied.</param>
+        public ConcurentObservableCollection(List<T> list) : base(list) { }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="ConcurentObservableCollection{T}"/> class that contains elements copied from the specified collection.
+        /// </summary>
+        /// <param name="collection">The collection from which the elements are copied.</param>
+        public ConcurentObservableCollection(IEnumerable<T> collection) : base(collection) { }
+
+        /// <inheritdoc cref="ObservableCollection{T}.ClearItems"/>
+        protected override void ClearItems()
+        {
+            lock (_lockObject)
+            {
+                base.ClearItems();
+            }
+        }
+
+        /// <inheritdoc cref="ObservableCollection{T}.RemoveItem"/>
+        protected override void RemoveItem(int index)
+        {
+            lock (_lockObject)
+            {
+                base.RemoveItem(index);
+            }
+        }
+
+        /// <inheritdoc cref="ObservableCollection{T}.InsertItem"/>
+        protected override void InsertItem(int index, T item)
+        {
+            lock (_lockObject)
+            {
+                base.InsertItem(index, item);
+            }
+        }
+
+        /// <inheritdoc cref="ObservableCollection{T}.SetItem"/>
+        protected override void SetItem(int index, T item)
+        {
+            lock (_lockObject)
+            {
+                base.SetItem(index, item);
+            }
+        }
+
+        /// <inheritdoc cref="ObservableCollection{T}.MoveItem"/>
+        protected override void MoveItem(int oldIndex, int newIndex)
+        {
+            lock (_lockObject)
+            {
+                base.MoveItem(oldIndex, newIndex);
+            }
+        }
+    }
+}