Play! framework form validations

Users.java

package controllers;
// Java
import java.util.*;
// Play
import play.*;
import play.mvc.*;
import play.libs.Json;
import play.data.validation.Constraints;
import play.data.Form;
import models.*;
// JSON
import com.fasterxml.jackson.databind.JsonNode;

public class Users extends Controller {
    public static Result newUser() {
      Form<UserCreate> userCreateForm = Form.form(UserCreate.class);
      userCreateForm = userCreateForm.bind(request().body().asJson());
      if (userCreateForm.hasErrors()) {
        return badRequest(userCreateForm.errorsAsJson());
      } else {
        UserCreate userCreate = userCreateForm.bindFromRequest().get();
        User user = User.create(userCreate.email);
        return created(Json.toJson(user));
      }
    }

    public static class UserCreate {
      @Constraints.Required
      public String email;
    }
}