Post review improvements

Author: jakipatryk

README.md

@@ -225,7 +225,9 @@ val registration = OpenAPIModelRegistration(
   components,
   config = RegistrationConfig(
     OpenAPIModelRegistration.RegistrationConfig(
-      sumADTsShape = OpenAPIModelRegistration.RegistrationConfig.SumADTsShape.WithDiscriminator()
+      sumADTsShape =
+         // default values apply for discriminatorPropertyNameFn, addDiscriminatorPropertyOnlyToDirectChildren
+         OpenAPIModelRegistration.RegistrationConfig.SumADTsShape.WithDiscriminator()
     )
   )
 )

library/src/main/scala/za/co/absa/springdocopenapiscala/OpenAPIModelRegistration.scala

@@ -160,7 +160,10 @@ class OpenAPIModelRegistration(
           val constEnumSchema = createConstEnumSchema(discriminatorValue.getOrElse(name))
           actualSchema.addProperty(discriminatorPropertyName, constEnumSchema)
           actualSchema.addRequiredItem(discriminatorPropertyName)
-        } else if (!addOnlyToDirectChildren && Option(actualSchema.getOneOf).map(!_.isEmpty).getOrElse(false)) {
+        } else if (
+          !addOnlyToDirectChildren &&
+          Option(actualSchema.getOneOf).map(!_.isEmpty).getOrElse(false) // is schema representing another sum ADT root
+        ) {
           addDiscriminatorPropertyToChildren(
             actualSchema,
             discriminatorPropertyName,