First pass at interface breakup
diff --git a/src/ProtocolBuffers/GeneratedExtensionLite.cs b/src/ProtocolBuffers/GeneratedExtensionLite.cs
new file mode 100644
index 0000000..2679451
--- /dev/null
+++ b/src/ProtocolBuffers/GeneratedExtensionLite.cs
@@ -0,0 +1,24 @@
+using System;
+
+namespace Google.ProtocolBuffers {
+
+  public interface IGeneratedExtensionLite {
+    int Number { get; }
+    object ContainingType { get; }
+    IMessageLite MessageDefaultInstance { get; }
+  }
+
+  public class GeneratedExtensionLite : IGeneratedExtensionLite {
+    public int Number {
+      get { throw new NotImplementedException(); }
+    }
+
+    public object ContainingType {
+      get { throw new NotImplementedException(); }
+    }
+
+    public IMessageLite MessageDefaultInstance {
+      get { throw new NotImplementedException(); }
+    }
+  }
+}
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