ServerManagers/src/ServerManager.WebApplication/Extensions/SwaggerDefaultValues.cs

using Microsoft.AspNetCore.Mvc.ApiExplorer;
using Microsoft.OpenApi.Models;
using Swashbuckle.AspNetCore.SwaggerGen;
using System.Linq;
using System.Text.Json;

namespace ServerManager.WebApplication.Extensions
{
    public class SwaggerDefaultValues : IOperationFilter
    {
        public void Apply(OpenApiOperation operation, OperationFilterContext context)
        {
            var apiDescription = context.ApiDescription;

            operation.Deprecated |= apiDescription.IsDeprecated();

            foreach (var responseType in context.ApiDescription.SupportedResponseTypes)
            {
                var responseKey = responseType.IsDefaultResponse ? "default" : responseType.StatusCode.ToString();
                var response = operation.Responses[responseKey];

                foreach (var contentType in response.Content.Keys)
                {
                    if (!responseType.ApiResponseFormats.Any(x => x.MediaType == contentType))
                    {
                        response.Content.Remove(contentType);
                    }
                }
            }

            if (operation.Parameters is null)
            {
                return;
            }

            foreach (var parameter in operation.Parameters)
            {
                var description = apiDescription.ParameterDescriptions
                                                .First(p => p.Name == parameter.Name);

                if (parameter.Description is null)
                {
                    parameter.Description = description.ModelMetadata?.Description;
                }

                if (parameter.Schema.Default is null && description.DefaultValue is not null)
                {
                    var json = JsonSerializer.Serialize(description.DefaultValue, description.ModelMetadata.ModelType);
                    parameter.Schema.Default = OpenApiAnyFactory.CreateFromJson(json);
                }

                parameter.Required |= description.IsRequired;
            }
        }
    }
}