fix build warnings on CSharp xml comments

modules/swagger-codegen/src/main/resources/csharp/ApiClient.mustache

@@ -216,6 +216,7 @@ namespace {{packageName}}.Client
         /// </summary>
         /// <param name="content">HTTP body (e.g. string, JSON).</param>
         /// <param name="type">Object type.</param>
+        /// <param name="headers"></param>
         /// <returns>Object representation of the JSON string.</returns>
         public object Deserialize(string content, Type type, IList<Parameter> headers=null)
         {

modules/swagger-codegen/src/main/resources/csharp/ApiException.mustache

@@ -20,7 +20,6 @@ namespace {{packageName}}.Client {
       /// <summary>
       /// Initializes a new instance of the <see cref="ApiException"/> class.
       /// </summary>
-      /// <param name="basePath">The base path.</param>
       public ApiException() {}
 
       /// <summary>

modules/swagger-codegen/src/main/resources/csharp/api.mustache

@@ -9,6 +9,9 @@ using {{packageName}}.Client;
 namespace {{packageName}}.Api
 {
     {{#operations}}
+    /// <summary>
+    /// Represents a collection of functions to interact with the API endpoints
+    /// </summary>
     public interface I{{classname}}
     {
         {{#operation}}
@@ -77,7 +80,7 @@ namespace {{packageName}}.Api
         /// <summary>
         /// Gets or sets the API client.
         /// </summary>
-        /// <value>An instance of the ApiClient</param>
+        /// <value>An instance of the ApiClient</value>
         public ApiClient ApiClient {get; set;}
     
         {{#operation}}