Remove SigV4 auth requirement for GetTokensFromRefreshToken

Author: aws-sdk-dotnet-automation

generator/ServiceModels/cognito-idp/cognito-idp-2016-04-18.api.json

@@ -1329,7 +1329,9 @@
         {"shape":"ForbiddenException"},
         {"shape":"RefreshTokenReuseException"},
         {"shape":"InternalErrorException"}
-      ]
+      ],
+      "authtype":"none",
+      "auth":["smithy.api#noAuth"]
     },
     "GetUICustomization":{
       "name":"GetUICustomization",

generator/ServiceModels/cognito-idp/cognito-idp-2016-04-18.normal.json

@@ -1398,7 +1398,9 @@
         {"shape":"RefreshTokenReuseException"},
         {"shape":"InternalErrorException"}
       ],
-      "documentation":"<p>Given a refresh token, issues new ID, access, and optionally refresh tokens for the user who owns the submitted token. This operation issues a new refresh token and invalidates the original refresh token after an optional grace period when refresh token rotation is enabled. If refresh token rotation is disabled, issues new ID and access tokens only.</p>"
+      "documentation":"<p>Given a refresh token, issues new ID, access, and optionally refresh tokens for the user who owns the submitted token. This operation issues a new refresh token and invalidates the original refresh token after an optional grace period when refresh token rotation is enabled. If refresh token rotation is disabled, issues new ID and access tokens only.</p>",
+      "authtype":"none",
+      "auth":["smithy.api#noAuth"]
     },
     "GetUICustomization":{
       "name":"GetUICustomization",

sdk/src/Services/CognitoIdentityProvider/Generated/Model/GetTokensFromRefreshTokenRequest.cs

@@ -25,6 +25,7 @@
 
 using Amazon.Runtime;
 using Amazon.Runtime.Internal;
+using Amazon.Runtime.Internal.Auth;
 
 #pragma warning disable CS0612,CS0618,CS1570
 namespace Amazon.CognitoIdentityProvider.Model
@@ -186,5 +187,13 @@ internal bool IsSetRefreshToken()
             return this._refreshToken != null;
         }
 
+        /// <summary>
+        /// Get the signer to use for this request.
+        /// </summary>
+        /// <returns>A signer for this request.</returns>
+        override protected AbstractAWSSigner CreateSigner()
+        {
+            return new NullSigner();
+        }
     }
 }