public Map<String, Validator> getValidations() {
return ImmutableMap.<String, Validator>builder()
.put(USERNAME, new LimitedStringValidator(1, MAX_USERNAME_LENGTH))
.put(PASSWORD, new FilledStringValidator())
.put(EMAIL, new LimitedStringValidator(1, MAX_EMAIL_LENGTH))
.put(FULL_NAME, new LimitedOptionalStringValidator(MAX_FULL_NAME_LENGTH))
.put(PERMISSIONS, new ListValidator())
.build();
}