You can declare additional validations and metadata for your parameters.

Generic validations and metadata:

* `alias`
* `title`
* `description`
* `deprecated`

Validations specific for strings:

* `min_length`
* `max_length`
* `pattern`

Custom validations using `AfterValidator`.

In these examples you saw how to declare validations for `str` values.

        } catch (SMBProtocolDecodingException e) {
            // If exception thrown, validation is working
            assertTrue(e.getMessage().contains("Invalid negotiate context data length") || e.getMessage().contains("Buffer too small")
                    || e.getMessage().contains("negotiate context"), "Validation detected issue: " + e.getMessage());
        }

Mais, **tout fonctionne** par défaut.

### Validation

* Validation pour la plupart (ou tous?) les **types de données** Python incluant:
    * objets JSON (`dict`).
    * listes JSON (`list`) définissant des types d'éléments.
    * Champs String (`str`), définition de longueur minimum ou maximale.
    * Nombres (`int`, `float`) avec valeur minimale and maximale, etc.

* Validation pour des types plus exotiques, tel que:
    * URL.

 */
package org.codelibs.fess.validation;

import java.lang.annotation.Annotation;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.util.Set;

import org.codelibs.fess.unit.UnitFessTestCase;

import jakarta.validation.ConstraintViolation;
import jakarta.validation.Validation;
import jakarta.validation.Validator;
import jakarta.validation.ValidatorFactory;

                                                 data-validation="custom"
                                                 data-validation-regexp="(\+|\-)?\d+(\.\d+)?((e|E)(\+|\-)?\d+)?"
                                                 data-validation-help="number (Float)"/>
                                    </div>
                                </div>

Another big feature needed by APIs is data validation, making sure that the data is valid, given certain parameters. For example, that some field is an `int`, and not some random string. This is especially useful for incoming data.

Without a data validation system, you would have to do all the checks by hand, in code.

each(function(c,d){d.validationConfig=b;var e=a(d);e.trigger("formValidationSetup",[e,b]),e.find(".has-help-txt").unbind("focus.validation").unbind("blur.validation"),e.removeClass("has-validation-callback").unbind("submit.validation").unbind("reset.validation").find("input[data-validation],textarea[data-validation]").unbind("blur.validation"),e.bind("submit.validation",function(c){var d=a(this),e=function(){return c.stopImmediatePropagation(),!1};if(a.formUtils.haltValidation)return e();if(a.fo...

La validation des données est une autre fonctionnalité importante dont ont besoin les API. Elle permet de s'assurer
que les données sont valides, compte tenu de certains paramètres. Par exemple, qu'un champ est un `int`, et non un
string.
Ceci est particulièrement utile pour les données entrantes.

 */
package org.codelibs.fess.app.web.admin.general;

import org.lastaflute.web.validation.Required;
import org.lastaflute.web.validation.theme.conversion.ValidateTypeFailure;

import jakarta.validation.constraints.Max;
import jakarta.validation.constraints.Min;
import jakarta.validation.constraints.Size;

/**
 * Form class for editing general system settings in the admin interface.

      }

    /**
     * Add a header with the specified name and value. Does validation of header names and values.
     */
    fun add(
      name: String,
      value: String,
    ) = commonAdd(name, value)

    /**
     * Add a header with the specified name and value. Does validation of header names, allowing
     * non-ASCII values.
     */
    fun addUnsafeNonAscii(