多亏了@Helen，我才能以如下方式执行此任务：
首先，您应该安装openAPI.NET和openAPI.NET Reader nuget包。

StreamReader reader = File.OpenText("yourswaggerDocfilename");
var doc = reader.ReadToEnd();
var openApiReader = new OpenApiStringReader();
var docDeserialized = openApiReader.ReadFragment<IOpenApiAny>(text, OpenApiSpecVersion.OpenApi2_0, out var _) as Dictionary<string, IOpenApiAny>;
var paths = openApidoc["paths"] as Dictionary<string, IOpenApiAny>;
foreach(var pathItem in paths)
{
    var methods = pathItem.Value as Dictionary<string, IOpenApiAny>;
    foreach(var methodItem in methods)
    {
        var operationFields = methodItem.Value as Dictionary<string, IOpenApiAny>;
        if (operationFields.ContainsKey("x-vendorExtension"))
        {
           var moduleNameObject = operationFields["x-vendorExtension"] as OpenApiString;
           Console.WriteLine($"{pathItem.Key} : {moduleNameObject.Value}");
        }
    }
}

你可以用下面的代码来解析swagger Doc

var openApiReader = new OpenApiStringReader();
var docDeserialized = openApiReader.Read(doc,var out _);

但是当doc包含任何大于decimal.MaxValue的值时，这将抛出OverflowException，因为这个nugget库在内部使用decimal.Parse()来解析Doc中的数字。