Support string ApiException.Content when actual

type is ValidationApiException.

fixes reactiveui/refit#636

Refit.Tests/ResponseTests.cs

@@ -221,6 +221,31 @@ namespace Refit.Tests
             Assert.NotNull(actualException.Content);
             Assert.Equal("Hello world", actualException.Content);
         }
+
+        [Fact]
+        public async Task ValidationApiException_HydratesBaseContent()
+        {
+            var expectedProblemDetails = new ProblemDetails
+            {
+                Detail = "detail",
+                Instance = "instance",
+                Status = 1,
+                Title = "title",
+                Type = "type"
+            };
+            var expectedContent = JsonConvert.SerializeObject(expectedProblemDetails);
+            var expectedResponse = new HttpResponseMessage(HttpStatusCode.BadRequest)
+            {
+                Content = new StringContent(expectedContent)
+            };
+            expectedResponse.Content.Headers.ContentType = new MediaTypeHeaderValue("application/problem+json");
+            mockHandler.Expect(HttpMethod.Get, "http://api/aliasTest")
+                .Respond(req => expectedResponse);
+
+            var actualException = await Assert.ThrowsAsync<ValidationApiException>(() => fixture.GetTestObject());
+            var actualBaseExcpetion = actualException as ApiException;
+            Assert.Equal(expectedContent, actualBaseExcpetion.Content);
+        }
     }
 
     public sealed class ThrowOnGetLengthMemoryStream : MemoryStream

Refit/ApiException.cs

@@ -53,11 +53,13 @@ namespace Refit
             try
             {
                 exception.ContentHeaders = response.Content.Headers;
-                exception.Content = await response.Content.ReadAsStringAsync().ConfigureAwait(false);
+                var content = await response.Content.ReadAsStringAsync().ConfigureAwait(false);
+                exception.Content = content;
 
                 if (response.Content.Headers?.ContentType?.MediaType?.Equals("application/problem+json") ?? false)
                 {
                     exception = await ValidationApiException.Create(exception).ConfigureAwait(false);
+                    exception.Content = content;
                 }
 
                 response.Content.Dispose();