How to use the @loopback/repository.isBuiltinType function in @loopback/repository

if (metaProperty.required && !(partial || optional)) {
      result.required = result.required ?? [];
      result.required.push(p);
    }

    // populating JSON Schema 'definitions'
    // shimks: ugly type casting; this should be replaced by logic to throw
    // error if itemType/type is not a string or a function
    const resolvedType = resolveType(metaProperty.type) as string | Function;
    const referenceType = isArrayType(resolvedType)
      ? // shimks: ugly type casting; this should be replaced by logic to throw
        // error if itemType/type is not a string or a function
        resolveType(metaProperty.itemType as string | Function)
      : resolvedType;

    if (typeof referenceType !== 'function' || isBuiltinType(referenceType)) {
      continue;
    }

    const propSchema = getJsonSchema(referenceType, options);

    includeReferencedSchema(referenceType.name, propSchema);
  }

  result.additionalProperties = meta.settings.strict === false;
  debug('  additionalProperties?', result.additionalProperties);

  if (options.includeRelations) {
    for (const r in meta.relations) {
      result.properties = result.properties ?? {};
      const relMeta = meta.relations[r];
      const targetType = resolveType(relMeta.target);

}
    result = {type: 'array', items: propDef};
    propertyType = meta.itemType as string | Function;
  } else {
    result = propDef;
  }

  const wrappedType = stringTypeToWrapper(propertyType);
  const resolvedType = resolveType(wrappedType);

  if (resolvedType === Date) {
    Object.assign(propDef, {
      type: 'string',
      format: 'date-time',
    });
  } else if (isBuiltinType(resolvedType)) {
    Object.assign(propDef, {
      type: resolvedType.name.toLowerCase(),
    });
  } else {
    Object.assign(propDef, {$ref: `#/definitions/${resolvedType.name}`});
  }

  if (meta.description) {
    Object.assign(propDef, {
      description: meta.description,
    });
  }

  if (meta.jsonSchema) {
    Object.assign(propDef, meta.jsonSchema);
  }