```Python
item: Item
```

...and with that single declaration you get:

* Editor support, including:
    * Completion.
    * Type checks.
* Validation of data:
    * Automatic and clear errors when the data is invalid.
    * Validation even for deeply nested JSON objects.

import org.lastaflute.web.response.HtmlResponse;
import org.lastaflute.web.response.render.RenderData;
import org.lastaflute.web.ruts.process.ActionRuntime;
import org.lastaflute.web.validation.VaErrorHook;
import org.lastaflute.web.validation.exception.ValidationErrorException;

import jakarta.annotation.Resource;

/**
 * @author shinsuke
 * @author Keiichi Watanabe
 */

So, even with the code above that doesn't use Pydantic explicitly, FastAPI is using Pydantic to convert those standard dataclasses to Pydantic's own flavor of dataclasses.

And of course, it supports the same:

* data validation
* data serialization
* data documentation, etc.

This works the same way as with Pydantic models. And it is actually achieved in the same way underneath, using Pydantic.

/// info

	if !exists && hasSpaceBE(accessKey) {
		writeErrorResponseJSON(ctx, w, errorCodes.ToAPIErr(ErrAdminResourceInvalidArgument), r.URL)
		return
	}

	if !utf8.ValidString(accessKey) {
		writeErrorResponseJSON(ctx, w, errorCodes.ToAPIErr(ErrAddUserValidUTF), r.URL)
		return
	}

	checkDenyOnly := false
	if accessKey == cred.AccessKey {

import org.lastaflute.job.subsidiary.JobConcurrentExec;
import org.lastaflute.web.validation.RequiredValidator;
import org.lastaflute.web.validation.theme.typed.DoubleTypeValidator;
import org.lastaflute.web.validation.theme.typed.FloatTypeValidator;
import org.lastaflute.web.validation.theme.typed.IntegerTypeValidator;
import org.lastaflute.web.validation.theme.typed.LongTypeValidator;
import org.opensearch.search.sort.SortBuilder;

                            "content": {"application/json": {"schema": {}}},
                        },
                        "422": {
                            "description": "Validation Error",
                            "content": {
                                "application/json": {
                                    "schema": {

                            "content": {"application/json": {"schema": {}}},
                        },
                        "422": {
                            "description": "Validation Error",
                            "content": {
                                "application/json": {
                                    "schema": {

@file:Suppress("UnstableApiUsage")

import com.diffplug.gradle.spotless.SpotlessExtension
import com.vanniktech.maven.publish.MavenPublishBaseExtension
import com.vanniktech.maven.publish.SonatypeHost
import java.net.URI
import kotlinx.validation.ApiValidationExtension
import org.gradle.api.tasks.testing.logging.TestExceptionFormat
import org.jetbrains.dokka.gradle.DokkaTaskPartial
import org.jetbrains.kotlin.gradle.dsl.kotlinExtension

  // The set of valid time zone names and the time zone offset is loaded from the system-wide time zone
  // database by the API server during CronJob validation and the controller manager during execution.
  // If no system-wide time zone database can be found a bundled version of the database is used instead.

                    "schema": {
                        "$ref": "#/components/schemas/Item"
                    }
                }
            }
        },
        "422": {
            "description": "Validation Error",
            "content": {
                "application/json": {
                    "schema": {
                        "$ref": "#/components/schemas/HTTPValidationError"
                    }
                }