Convert XML data to JSON and return it from Web API

Recently I stumbled upon a situation where a large number of XML documents needed to be returned from ASP.NET Web API. This sounds like a straightforward task but there was a small twist to the story. The XML documents existed as physical disk files. The Web API should read these files and convert the XML data into JSON. This was needed because the client applications were designed to handle only JSON format. Here I discuss a quick way to accomplish this task.