refactor(query-set): error details for nested rel

Author: jaredcnance

src/JsonApiDotNetCore/Internal/Query/QuerySet.cs

@@ -147,6 +147,9 @@ private List<SortQuery> ParseSortParameters(string value)
 
         private List<string> ParseIncludedRelationships(string value)
         {
+            if(value.Contains("."))
+                throw new JsonApiException("400", "Deeply nested relationships are not supported");
+
             return value
                 .Split(',')
                 .Select(s => s.ToProperCase())

test/JsonApiDotNetCoreExampleTests/Acceptance/Spec/DocumentTests/Included.cs

@@ -234,7 +234,7 @@ public async Task Request_ToIncludeUnknownRelationship_Returns_400()
         }
 
         [Fact]
-        public async Task Request_ToIncludeRelationshipPath_Returns_400()
+        public async Task Request_ToIncludeDeeplyNestedRelationships_Returns_400()
         {
             // arrange
             var person = _context.People.First();