Trying to export csharp client

[robsoh09]

This error appears:

System.InvalidOperationException: The properties 'feeOptions' are defined multiple times.

Runtime: Default
at NJsonSchema.JsonSchema.get_ActualProperties()
at NJsonSchema.CodeGeneration.CSharp.Models.ClassTemplateModel..ctor(String typeName, CSharpGeneratorSettings settings, CSharpTypeResolver resolver, JsonSchema schema, Object rootObject)
at NJsonSchema.CodeGeneration.CSharp.CSharpGenerator.GenerateClass(JsonSchema schema, String typeName)
at NJsonSchema.CodeGeneration.GeneratorBase.GenerateTypes()
at NJsonSchema.CodeGeneration.CSharp.CSharpGenerator.GenerateTypes()
at NSwag.CodeGeneration.ClientGeneratorBase`3.GenerateFile(ClientGeneratorOutputType outputType)
at NSwag.Commands.CodeGeneration.OpenApiToCSharpClientCommand.d__107.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at NSwag.Commands.CodeGeneration.OpenApiToCSharpClientCommand.d__106.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at NSwag.Commands.NSwagDocument.<>c__DisplayClass8_1.<b__0>d.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at NSwag.Commands.NSwagDocument.d__8.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at NSwag.Commands.Document.ExecuteDocumentCommand.d__9.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at NSwag.Commands.Document.ExecuteDocumentCommand.d__8.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at NConsole.CommandLineProcessor.d__12.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
at NConsole.CommandLineProcessor.d__11.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at NSwag.Commands.NSwagCommandProcessor.d__3.MoveNext()

how can i troubleshoot this?