title: WCF WebService with warnings and InvalidOperationException
body: <p>I am currently trying to connect my ASP-NET Core 2 application to Magento's API (WSDL v2), but keep receiving the following errors:<br>
  *Doesn't matter which method I call, even the <code>new PortTypeClient().loginAsync(username, password);</code> throws that, with this random endpoint name <code>salesOrderShipmentAddComment</code>.</p>
  
  <blockquote>
    <p>InvalidOperationException: The operation
    'salesOrderShipmentAddComment' could not be loaded because it
    specifies \"rpc-style\" in \"literal\" mode, but uses message contract
    types or the System.ServiceModel.Channels.Message. This combination is
    disallowed -- specify a different value for style or use parameters
    other than message contract types or
    System.ServiceModel.Channels.Message.</p>
  </blockquote>
  
  <p>However, using SoapUI, postman or importing with framework 4.6, it works perfectly.
  Using the Magento v1 API it works too, but I don't want to use this version.</p>
  
  <p>During the import in asp-net core, I also recieve those warnings (importing v1 doesn't shows any warning):
  <a href="https://i.stack.imgur.com/ZXPnR.png" rel="noreferrer"><img src="https://i.stack.imgur.com/ZXPnR.png" alt="enter image description here"></a></p>
  
  <p>I'm almost creating a new 4.6 application, hosting it separately to work as a bridge between my application and Magento, even if it hurts my performance and architeture.</p>
  
  <p>This is how I'm doing the import:
  <a href="https://i.stack.imgur.com/vVozR.png" rel="noreferrer"><img src="https://i.stack.imgur.com/vVozR.png" alt="enter image description here"></a>
  *Obs: In <code>Data Type Options</code>, I also tried checking different options, and selecting other data types.</p>
  
  <p>Anything would help...<br>
  Thanks in advance</p>