function whitespace(rule, value, source, errors, options) {
  if (/^\s+$/.test(value) || value === '') {
    errors.push(__WEBPACK_IMPORTED_MODULE_0__util__["e" /* format */](options.messages.whitespace, rule.fullField));
  }
}
Rule for validating whitespace.

 @param rule The validation rule.
 @param value The value of the field on the source object.
 @param source The source object being validated.
 @param errors An array of errors that this rule may add
 validation errors to.
 @param options The validation options.
 @param options.messages The validation messages.