Fixed ConsistencyLevelEventual parameter by adding a default value for AdditionalHeaders parameter.

Author: reusto

src/Commands/Graph/InvokeGraphMethod.cs

@@ -64,7 +64,7 @@ public string Url
         [Parameter(Mandatory = false, ParameterSetName = ParameterSet_TOFILE)]
         [Parameter(Mandatory = false, ParameterSetName = ParameterSet_TOCONSOLE)]
         [Parameter(Mandatory = false, ParameterSetName = ParameterSet_TOSTREAM)]
-        public GraphAdditionalHeadersPipeBind AdditionalHeaders;
+        public GraphAdditionalHeadersPipeBind AdditionalHeaders = new GraphAdditionalHeadersPipeBind(new Dictionary<string, string>());
         // public IDictionary<string, string> AdditionalHeaders
         // {
         //     get