getExactConverter(name) {
    const converter = getConverter(name)
    const checker = getChecker(name)
    return (str) => {
      const result = converter(str)
      return checker(result) ? result : str /* cannot convert */
    }
  }
Return case exact converter.
If the converted result is not the correct case, the original value is returned.
@param { 'camelCase' | 'kebab-case' | 'PascalCase' | 'snake_case' } name type of converter to return ('camelCase', 'kebab-case', 'PascalCase')
@return {kebabCase|camelCase|pascalCase|snakeCase}