Minor sonar fixes

src/main/java/com/kobylynskyi/graphql/codegen/GraphQLDocumentParser.java

@@ -88,7 +88,6 @@ class GraphQLDocumentParser {
             populateDefinition(extendedDocumentBuilder.interfaceDefinitions, definition, definitionName,
                     InterfaceTypeExtensionDefinition.class, s -> new ExtendedInterfaceTypeDefinition());
         }
-        // TODO: consider DirectiveDefinition
     }
 
     @SuppressWarnings("unchecked")

src/main/java/com/kobylynskyi/graphql/codegen/mapper/GraphqlTypeToJavaTypeMapper.java

@@ -262,7 +262,7 @@ class GraphqlTypeToJavaTypeMapper {
                 // in case it is subscription and subscriptionReturnType is set
                 return getGenericsString(mappingContext.getSubscriptionReturnType(), javaTypeName);
             }
-        } else if (mappingContext.getUseOptionalForNullableReturnTypes()) {
+        } else if (Boolean.TRUE.equals(mappingContext.getUseOptionalForNullableReturnTypes())) {
             // wrap the type into java.util.Optional (except lists)
             if (!namedDefinition.isMandatory() && !javaTypeName.startsWith(JAVA_UTIL_LIST)) {
                 return getGenericsString(JAVA_UTIL_OPTIONAL, javaTypeName);