Update JsonInheritanceConverter.liquid (#1502)

* Update JsonInheritanceConverter.liquid

The InheritanceConverters needs to be made public so downstream NSwag Generator can get the DiscriminatorName (i.e. wrapping Client classes in another generated client class)

Error below:
6> ---> Microsoft.CSharp.RuntimeBinder.RuntimeBinderException: 'System.Text.Json.Serialization.JsonConverter<BaseClass>' does not contain a definition for 'DiscriminatorName'

* updated missing namepace for JsonException

* fix unit tests

Co-authored-by: Mike Mao <Mike.Mao@NZFUNDS.CO.NZ>

src/NJsonSchema.CodeGeneration.CSharp.Tests/InheritanceInterfaceTests.cs

@@ -57,7 +57,7 @@ public async Task When_schema_has_base_schema_then_it_is_referenced_with_Newtons
             Assert.True(json.Properties["Item"].ActualTypeSchema.AllOf.First().HasReference);
             Assert.Contains("[Newtonsoft.Json.JsonConverter(typeof(JsonInheritanceConverter), \"discriminator\")]", code);
             Assert.Contains("[JsonInheritanceAttribute(\"Banana\", typeof(Banana))]", code);
-            Assert.Contains("internal class JsonInheritanceConverter : Newtonsoft.Json.JsonConverter", code);
+            Assert.Contains("public class JsonInheritanceConverter : Newtonsoft.Json.JsonConverter", code);
         }
 
         [Fact]
@@ -76,7 +76,7 @@ public async Task When_schema_has_base_schema_then_it_is_referenced_with_STJ()
             Assert.True(json.Properties["Item"].ActualTypeSchema.AllOf.First().HasReference);
             Assert.Contains("[JsonInheritanceConverter(typeof(Fruit), \"discriminator\")]", code);
             Assert.Contains("[JsonInheritanceAttribute(\"Banana\", typeof(Banana))]", code);
-            Assert.Contains("internal class JsonInheritanceConverter<TBase> : System.Text.Json.Serialization.JsonConverter<TBase>", code);
+            Assert.Contains("public class JsonInheritanceConverter<TBase> : System.Text.Json.Serialization.JsonConverter<TBase>", code);
         }
     }
 }

src/NJsonSchema.CodeGeneration.CSharp/Templates/JsonInheritanceConverter.liquid

@@ -11,7 +11,7 @@ internal class JsonInheritanceConverterAttribute : System.Text.Json.Serializatio
     }
 }
 
-internal class JsonInheritanceConverter<TBase> : System.Text.Json.Serialization.JsonConverter<TBase>
+public class JsonInheritanceConverter<TBase> : System.Text.Json.Serialization.JsonConverter<TBase>
 {
     private readonly string _discriminatorName;
 
@@ -115,7 +115,7 @@ internal class JsonInheritanceConverter<TBase> : System.Text.Json.Serialization.
     }
 }
 {%- else -%}
-internal class JsonInheritanceConverter : Newtonsoft.Json.JsonConverter
+public class JsonInheritanceConverter : Newtonsoft.Json.JsonConverter
 {
     internal static readonly string DefaultDiscriminatorName = "discriminator";
 
@@ -235,4 +235,4 @@ internal class JsonInheritanceConverter : Newtonsoft.Json.JsonConverter
         return objectType.Name;
     }
 }
-{%- endif -%}
+{%- endif -%}