Add tracingheader for support Diagnostics

src/DotNetCore.CAP/Diagnostics/TracingHeaders.cs

+// Copyright (c) .NET Core Community. All rights reserved.
+// Licensed under the MIT License. See License.txt in the project root for license information.
+
+using System.Collections;
+using System.Collections.Generic;
+using System.Linq;
+
+namespace DotNetCore.CAP.Diagnostics
+{
+    public class TracingHeaders : IEnumerable<KeyValuePair<string, string>>
+    {
+        private List<KeyValuePair<string, string>> _dataStore;
+
+        public IEnumerator<KeyValuePair<string, string>> GetEnumerator()
+        {
+            return _dataStore.GetEnumerator();
+        }
+
+        IEnumerator IEnumerable.GetEnumerator()
+        {
+            return GetEnumerator();
+        }
+
+        public void Add(string name, string value)
+        {
+            if (_dataStore == null)
+            {
+                _dataStore = new List<KeyValuePair<string, string>>();
+            }
+
+            _dataStore.Add(new KeyValuePair<string, string>(name, value));
+        }
+
+        public bool Contains(string name)
+        {
+            return _dataStore != null && _dataStore.Any(x => x.Key == name);
+        }
+
+        public void Remove(string name)
+        {
+            _dataStore?.RemoveAll(x => x.Key == name);
+        }
+
+        public void Cleaar()
+        {
+            _dataStore?.Clear();
+        }
+    }
+}
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