void initializeDocType() {
                Set<String> importedFields = new HashSet<>();
                for (var imported : docTypeConfig.importedfield()) {
                    importedFields.add(imported.name());
                }
                int contentIdx = docTypeConfig.contentstruct();
                DataType contentStruct = typesByIdx.get(contentIdx);
                if (! (contentStruct instanceof StructDataType)) {
                    throw new IllegalArgumentException("Content struct for document type "+docTypeConfig.name()+
                                                       " should be a struct, but was: "+contentStruct);
                }
                if (docTypeConfig.name().equals(DataType.DOCUMENT.getName())) {
                    this.docType = DataType.DOCUMENT;
                } else {
                    this.docType = new DocumentType(docTypeConfig.name(), (StructDataType)contentStruct, importedFields);
                }
                addNewType(docTypeConfig.idx(), docType);
            }
One-shot configuration; should be called on a newly constructed manager
document/src/main/java/com/yahoo/document/DocumentTypeManagerConfigurer.java