Fixed issue with nullability inference of nested types. (#6230)

Co-authored-by: Anton Tykhyy <atykhyy@gmail.com>

src/HotChocolate/Core/src/Types/Internal/ExtendedType.Tools.cs

@@ -144,7 +144,7 @@ internal static bool IsNonGenericBaseType(Type type)
             }
 
             written = buffer.Length;
-            return false;
+            return true;
         }
     }
 }

src/HotChocolate/Core/test/Types.Tests/CodeFirstTests.cs

@@ -186,6 +186,18 @@ public async Task Allow_PascalCasedArguments()
             """);
     }
 
+    [Fact]
+    public async Task Infer_Nullability_From_Nested_Classes()
+    {
+        var schema =
+            await new ServiceCollection()
+                .AddGraphQLServer()
+                .AddQueryType<QueryNestedClassNullableString>()
+                .BuildSchemaAsync();
+
+        schema.MatchSnapshot();
+    }
+
     public class Query
     {
         public string SayHello(string name) =>
@@ -324,4 +336,28 @@ public class PascalCaseQuery
     {
         public string TestResolver(string TestArgument) => "abc";
     }
+
+    public sealed class QueryNestedClassNullableString
+    {
+        public class Outer
+        {
+            public string? shouldBeNullable { get; set; }
+        }
+
+        public class Example
+        {
+            public class Inner
+            {
+                public string? shouldAlsoBeNullable { get; set; }
+            }
+
+            public Inner? inner { get; set; } = new();
+            public Outer? outer { get; set; } = new();
+        }
+
+        public Example NestedClassNullableString()
+        {
+            return new Example();
+        }
+    }
 }

src/HotChocolate/Core/test/Types.Tests/Internal/ExtendedTypeTests.cs

@@ -388,6 +388,19 @@ public void From_IExecutableScalar()
         Assert.True(dict.IsArrayOrList);
     }
 
+    [Fact]
+    public void Nested_Nullability()
+    {
+        // arrange
+        // act
+        var extendedType = ExtendedType.FromMember(
+            typeof(Nullability).GetMember("NestedProp").Single(),
+            _cache);
+
+        // assert
+        Assert.True(extendedType.IsNullable);
+    }
+
     private sealed class CustomStringList1
         : List<string>
     {
@@ -415,6 +428,13 @@ public class Nullability
 
         public Optional<Nullable<Optional<string?>>> OptionalNullableOptionalNullableString() =>
             throw new NotImplementedException();
+
+        public Nested? NestedProp { get; set; }
+
+        public class Nested
+        {
+            public string? Value { get; set; }
+        }
     }
 
 #nullable disable

src/HotChocolate/Core/test/Types.Tests/__snapshots__/CodeFirstTests.Infer_Nullability_From_Nested_Classes.graphql

@@ -0,0 +1,20 @@
+schema {
+  query: QueryNestedClassNullableString
+}
+
+type Example {
+  inner: Inner!
+  outer: Outer!
+}
+
+type Inner {
+  shouldAlsoBeNullable: String!
+}
+
+type Outer {
+  shouldBeNullable: String!
+}
+
+type QueryNestedClassNullableString {
+  nestedClassNullableString: Example!
+}