code: private void registerParentType(final Map<String, SchemaNode> schemaNodes, final SchemaNode parentSchemaNode, final Map<String, GraphQLType> graphQLTypes, final Map<String, GraphQLFieldDefinition> fields, final Set<String> blacklist) throws FrameworkException {
  
  		if (parentSchemaNode != null && !parentSchemaNode.equals(this)) {
  
  			final String parentName = parentSchemaNode.getClassName();
  			if (parentName != null && !blacklist.contains(parentName)) {
  
  				if (!graphQLTypes.containsKey(parentName)) {
  
  					// initialize parent type
  					parentSchemaNode.initializeGraphQL(schemaNodes, graphQLTypes, blacklist);
  				}
  
  				// second try: add fields from parent type
  				if (graphQLTypes.containsKey(parentName)) {
  
  					final GraphQLObjectType parentType = (GraphQLObjectType)graphQLTypes.get(parentName);
  					if (parentType != null) {
  
  						for (final GraphQLFieldDefinition field : parentType.getFieldDefinitions()) {
  
  							fields.put(field.getName(), field);
  						}
  					}
  				}
  			}
  		}
  
  	}
docs: ----- private methods -----