diff --git a/.travis.yml b/.travis.yml
index 34ed55fc..4d743018 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -6,6 +6,7 @@ branches:
   only:
     - master
     - 1.x
+    - 0.x
 
 language: php
 
diff --git a/composer.json b/composer.json
index 6a920fa0..9c2d607d 100644
--- a/composer.json
+++ b/composer.json
@@ -34,7 +34,7 @@
         "twig/twig": "^2.0 || ^3.0"
     },
     "conflict": {
-        "sonata-project/core-bundle": ">=3.13"
+        "sonata-project/core-bundle": "<3.19"
     },
     "require-dev": {
         "doctrine/persistence": "^1.1",
@@ -56,7 +56,7 @@
     },
     "extra": {
         "branch-alias": {
-            "dev-master": "1.x-dev"
+            "dev-master": "0.x-dev"
         }
     },
     "autoload": {
diff --git a/src/Bridge/Symfony/Bundle/SonataFormBundle.php b/src/Bridge/Symfony/Bundle/SonataFormBundle.php
index 96db3603..cbea288d 100644
--- a/src/Bridge/Symfony/Bundle/SonataFormBundle.php
+++ b/src/Bridge/Symfony/Bundle/SonataFormBundle.php
@@ -19,7 +19,7 @@
 final class SonataFormBundle extends Bundle
 {
     /**
-     * {@inheritdoc}
+     * @return string
      */
     public function getPath()
     {
@@ -27,7 +27,7 @@ public function getPath()
     }
 
     /**
-     * {@inheritdoc}
+     * @return string
      */
     protected function getContainerExtensionClass()
     {
diff --git a/src/DataTransformer/BooleanTypeToBooleanTransformer.php b/src/DataTransformer/BooleanTypeToBooleanTransformer.php
index 4e60c580..a2dd5490 100644
--- a/src/DataTransformer/BooleanTypeToBooleanTransformer.php
+++ b/src/DataTransformer/BooleanTypeToBooleanTransformer.php
@@ -16,9 +16,12 @@
 use Sonata\Form\Type\BooleanType;
 use Symfony\Component\Form\DataTransformerInterface;
 
-final class BooleanTypeToBooleanTransformer implements DataTransformerInterface
+/**
+ * @final since sonata-project/form-extensions 0.x
+ */
+class BooleanTypeToBooleanTransformer implements DataTransformerInterface
 {
-    public function transform($value): ?int
+    public function transform($value)
     {
         if (true === $value or BooleanType::TYPE_YES === (int) $value) {
             return BooleanType::TYPE_YES;
@@ -29,7 +32,7 @@ public function transform($value): ?int
         return null;
     }
 
-    public function reverseTransform($value): ?bool
+    public function reverseTransform($value)
     {
         if (BooleanType::TYPE_YES === $value) {
             return true;
diff --git a/src/Date/MomentFormatConverter.php b/src/Date/MomentFormatConverter.php
index 9502f29d..bd811b6e 100644
--- a/src/Date/MomentFormatConverter.php
+++ b/src/Date/MomentFormatConverter.php
@@ -56,7 +56,7 @@ class MomentFormatConverter
      *
      * @return string Moment.js date format
      */
-    public function convert(string $format): string
+    public function convert($format)
     {
         $size = \strlen($format);
 
diff --git a/src/EventListener/FixCheckboxDataListener.php b/src/EventListener/FixCheckboxDataListener.php
index acbf6b48..9f0ceb7c 100644
--- a/src/EventListener/FixCheckboxDataListener.php
+++ b/src/EventListener/FixCheckboxDataListener.php
@@ -24,15 +24,20 @@
  * returning true value when the form is bind.
  *
  * @author Sylvain Rascar <rascar.sylvain@gmail.com>
+ *
+ * @final since sonata-project/form-extensions 0.x
  */
-final class FixCheckboxDataListener implements EventSubscriberInterface
+class FixCheckboxDataListener implements EventSubscriberInterface
 {
-    public static function getSubscribedEvents(): array
+    /**
+     * @return array
+     */
+    public static function getSubscribedEvents()
     {
         return [FormEvents::PRE_SUBMIT => 'preSubmit'];
     }
 
-    public function preSubmit(FormEvent $event): void
+    public function preSubmit(FormEvent $event)
     {
         $data = $event->getData();
         $transformers = $event->getForm()->getConfig()->getViewTransformers();
diff --git a/src/EventListener/ResizeFormListener.php b/src/EventListener/ResizeFormListener.php
index c7d13c03..28966bbc 100644
--- a/src/EventListener/ResizeFormListener.php
+++ b/src/EventListener/ResizeFormListener.php
@@ -22,8 +22,10 @@
  * Resize a collection form element based on the data sent from the client.
  *
  * @author Bernhard Schussek <bernhard.schussek@symfony-project.com>
+ *
+ * @final since sonata-project/form-extensions 0.x
  */
-final class ResizeFormListener implements EventSubscriberInterface
+class ResizeFormListener implements EventSubscriberInterface
 {
     /**
      * @var string
@@ -67,7 +69,7 @@ public function __construct(
         $this->preSubmitDataCallback = $preSubmitDataCallback;
     }
 
-    public static function getSubscribedEvents(): array
+    public static function getSubscribedEvents()
     {
         return [
             FormEvents::PRE_SET_DATA => 'preSetData',
@@ -79,7 +81,7 @@ public static function getSubscribedEvents(): array
     /**
      * @throws UnexpectedTypeException
      */
-    public function preSetData(FormEvent $event): void
+    public function preSetData(FormEvent $event)
     {
         $form = $event->getForm();
         $data = $event->getData();
@@ -111,7 +113,7 @@ public function preSetData(FormEvent $event): void
     /**
      * @throws UnexpectedTypeException
      */
-    public function preSubmit(FormEvent $event): void
+    public function preSubmit(FormEvent $event)
     {
         if (!$this->resizeOnSubmit) {
             return;
@@ -158,7 +160,7 @@ public function preSubmit(FormEvent $event): void
     /**
      * @throws UnexpectedTypeException
      */
-    public function onSubmit(FormEvent $event): void
+    public function onSubmit(FormEvent $event)
     {
         if (!$this->resizeOnSubmit) {
             return;
diff --git a/src/Fixtures/StubFilesystemLoader.php b/src/Fixtures/StubFilesystemLoader.php
new file mode 100644
index 00000000..7b3b4167
--- /dev/null
+++ b/src/Fixtures/StubFilesystemLoader.php
@@ -0,0 +1,27 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * This file is part of the Sonata Project package.
+ *
+ * (c) Thomas Rabaix <thomas.rabaix@sonata-project.org>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Sonata\Form\Fixtures;
+
+use Twig\Loader\FilesystemLoader;
+
+final class StubFilesystemLoader extends FilesystemLoader
+{
+    protected function findTemplate($name, $throw = true)
+    {
+        // strip away bundle name
+        $parts = explode(':', $name);
+
+        return parent::findTemplate(end($parts), $throw);
+    }
+}
diff --git a/src/Serializer/BaseSerializerHandler.php b/src/Serializer/BaseSerializerHandler.php
index f47da0a9..a511215e 100644
--- a/src/Serializer/BaseSerializerHandler.php
+++ b/src/Serializer/BaseSerializerHandler.php
@@ -38,17 +38,26 @@ public function __construct(ManagerInterface $manager)
         $this->manager = $manager;
     }
 
-    final public static function setFormats(array $formats): void
+    /**
+     * @param string[] $formats
+     */
+    final public static function setFormats($formats)
     {
         static::$formats = $formats;
     }
 
-    final public static function addFormat(string $format): void
+    /**
+     * @param string $format
+     */
+    final public static function addFormat($format)
     {
         static::$formats[] = $format;
     }
 
-    public static function getSubscribingMethods(): array
+    /**
+     * @return array[]
+     */
+    public static function getSubscribingMethods()
     {
         $type = static::getType();
         $methods = [];
@@ -74,8 +83,12 @@ public static function getSubscribingMethods(): array
 
     /**
      * Serialize data object to id.
+     *
+     * @param object $data
+     *
+     * @return int|null
      */
-    public function serializeObjectToId(VisitorInterface $visitor, object $data, array $type, Context $context): ?int
+    public function serializeObjectToId(VisitorInterface $visitor, $data, $type, Context $context)
     {
         $className = $this->manager->getClass();
 
@@ -88,8 +101,12 @@ public function serializeObjectToId(VisitorInterface $visitor, object $data, arr
 
     /**
      * Deserialize object from its id.
+     *
+     * @param int $data
+     *
+     * @return object|null
      */
-    public function deserializeObjectFromId(VisitorInterface $visitor, int $data, array $type): ?object
+    public function deserializeObjectFromId(VisitorInterface $visitor, $data, array $type)
     {
         return $this->manager->findOneBy(['id' => $data]);
     }
diff --git a/src/Serializer/SerializerHandlerInterface.php b/src/Serializer/SerializerHandlerInterface.php
index 4f8c6525..cf0160b0 100644
--- a/src/Serializer/SerializerHandlerInterface.php
+++ b/src/Serializer/SerializerHandlerInterface.php
@@ -20,5 +20,8 @@
  */
 interface SerializerHandlerInterface extends SubscribingHandlerInterface
 {
-    public static function getType(): string;
+    /**
+     * @return string
+     */
+    public static function getType();
 }
diff --git a/src/Test/AbstractWidgetTestCase.php b/src/Test/AbstractWidgetTestCase.php
index bc39b5e8..b1183cf0 100644
--- a/src/Test/AbstractWidgetTestCase.php
+++ b/src/Test/AbstractWidgetTestCase.php
@@ -78,7 +78,7 @@ protected function getEnvironment(): Environment
      *
      * @return string[]
      */
-    protected function getTemplatePaths(): array
+    protected function getTemplatePaths()
     {
         // this is an workaround for different composer requirements and different TwigBridge installation directories
         $twigPaths = array_filter([
@@ -89,7 +89,7 @@ protected function getTemplatePaths(): array
             // symfony/symfony (running from this bundle)
             __DIR__.'/../../vendor/symfony/symfony/src/Symfony/Bridge/Twig/Resources/views/Form',
             // symfony/symfony (running from other bundles)
-            __DIR__.'/../../../../../symfony/symfony/src/Symfony/Bridge/Twig/Resources/views/Form',
+            __DIR__.'/../../../../symfony/symfony/src/Symfony/Bridge/Twig/Resources/views/Form',
         ], 'is_dir');
 
         $twigPaths[] = __DIR__.'/../Bridge/Symfony/Resources/views/Form';
@@ -97,32 +97,43 @@ protected function getTemplatePaths(): array
         return $twigPaths;
     }
 
-    protected function getRenderingEngine(Environment $environment): TwigRendererEngine
+    protected function getRenderingEngine(Environment $environment)
     {
         return new TwigRendererEngine(['form_div_layout.html.twig'], $environment);
     }
 
     /**
      * Renders widget from FormView, in SonataAdmin context, with optional view variables $vars. Returns plain HTML.
+     *
+     * @return string
      */
-    final protected function renderWidget(FormView $view, array $vars = []): string
+    final protected function renderWidget(FormView $view, array $vars = [])
     {
         return (string) $this->renderer->searchAndRenderBlock($view, 'widget', $vars);
     }
 
     /**
      * Helper method to strip newline and space characters from html string to make comparing easier.
+     *
+     * @param string $html
+     *
+     * @return string
      */
-    final protected function cleanHtmlWhitespace(string $html): string
+    final protected function cleanHtmlWhitespace($html)
     {
-        return preg_replace_callback('/\s*>([^<]+)</', static function (array $value): string {
+        return preg_replace_callback('/\s*>([^<]+)</', static function ($value) {
             return '>'.trim($value[1]).'<';
         }, $html);
     }
 
-    final protected function cleanHtmlAttributeWhitespace(string $html): string
+    /**
+     * @param string $html
+     *
+     * @return string
+     */
+    final protected function cleanHtmlAttributeWhitespace($html)
     {
-        return preg_replace_callback('~<([A-Z0-9]+) \K(.*?)>~i', static function (array $m): string {
+        return preg_replace_callback('~<([A-Z0-9]+) \K(.*?)>~i', static function ($m) {
             return preg_replace('~\s*~', '', $m[0]);
         }, $html);
     }
diff --git a/src/Type/BaseDoctrineORMSerializationType.php b/src/Type/BaseDoctrineORMSerializationType.php
index cc8af366..7dbc7d2b 100644
--- a/src/Type/BaseDoctrineORMSerializationType.php
+++ b/src/Type/BaseDoctrineORMSerializationType.php
@@ -78,7 +78,7 @@ public function __construct(MetadataFactoryInterface $metadataFactory, ManagerRe
         $this->identifierOverwrite = $identifierOverwrite;
     }
 
-    public function buildForm(FormBuilderInterface $builder, array $options): void
+    public function buildForm(FormBuilderInterface $builder, array $options)
     {
         $serializerMetadata = $this->metadataFactory->getMetadataForClass($this->class);
 
@@ -147,7 +147,7 @@ public function getName()
         return $this->getBlockPrefix();
     }
 
-    public function configureOptions(OptionsResolver $resolver): void
+    public function configureOptions(OptionsResolver $resolver)
     {
         $resolver->setDefaults([
             'data_class' => $this->class,
diff --git a/src/Type/BasePickerType.php b/src/Type/BasePickerType.php
index a725429a..38ea6d5b 100644
--- a/src/Type/BasePickerType.php
+++ b/src/Type/BasePickerType.php
@@ -46,13 +46,17 @@ abstract class BasePickerType extends AbstractType
      */
     private $formatConverter;
 
-    public function __construct(MomentFormatConverter $formatConverter, $translator, ?RequestStack $requestStack = null)
+    /**
+     * @param LegacyTranslatorInterface|TranslatorInterface|null $translator
+     */
+    public function __construct(MomentFormatConverter $formatConverter, $translator = null, ?RequestStack $requestStack = null)
     {
-        if (!$translator instanceof LegacyTranslatorInterface && !$translator instanceof TranslatorInterface) {
+        if (!$translator instanceof LegacyTranslatorInterface && !$translator instanceof TranslatorInterface && null !== $translator) {
             throw new \InvalidArgumentException(sprintf(
-                'Argument 2 should be an instance of %s or %s',
+                'Argument 2 should be an instance of %s or %s or %s',
                 LegacyTranslatorInterface::class,
-                TranslatorInterface::class
+                TranslatorInterface::class,
+                'null'
             ));
         }
 
@@ -65,7 +69,7 @@ public function __construct(MomentFormatConverter $formatConverter, $translator,
             }
 
             @trigger_error(sprintf(
-                'Not passing the request stack as argument 3 to %s() is deprecated since sonata-project/form-extensions 1.2 and will be mandatory in 2.0.',
+                'Not passing the request stack as argument 3 to %s() is deprecated since sonata-project/form-extensions 0.x and will be mandatory in 2.0.',
                 __METHOD__
             ), E_USER_DEPRECATED);
         }
@@ -75,15 +79,23 @@ public function __construct(MomentFormatConverter $formatConverter, $translator,
 
         if ($translator instanceof LegacyTranslatorInterface) {
             $this->locale = $this->translator->getLocale();
-        } else {
+        } elseif ($translator instanceof TranslatorInterface) {
             $this->locale = $this->getLocale($requestStack);
+        } else {
+            /*
+             * NEXT_MAJOR: remove this check
+             */
+            @trigger_error(
+                'Initializing '.__CLASS__.' without TranslatorInterface
+                is deprecated since 0.x and will be removed in 1.0.',
+                E_USER_DEPRECATED
+            );
+
+            $this->locale = \Locale::getDefault();
         }
     }
 
-    /**
-     * {@inheritdoc}
-     */
-    public function configureOptions(OptionsResolver $resolver): void
+    public function configureOptions(OptionsResolver $resolver)
     {
         $resolver->setNormalizer('format', function (Options $options, $format) {
             if (isset($options['date_format']) && \is_string($options['date_format'])) {
@@ -112,7 +124,7 @@ public function configureOptions(OptionsResolver $resolver): void
         });
     }
 
-    public function finishView(FormView $view, FormInterface $form, array $options): void
+    public function finishView(FormView $view, FormInterface $form, array $options)
     {
         $format = $options['format'];
 
@@ -149,8 +161,10 @@ public function finishView(FormView $view, FormInterface $form, array $options):
 
     /**
      * Gets base default options for the date pickers.
+     *
+     * @return array
      */
-    protected function getCommonDefaults(): array
+    protected function getCommonDefaults()
     {
         return [
             'widget' => 'single_text',
diff --git a/src/Type/BaseStatusType.php b/src/Type/BaseStatusType.php
index a3def1fb..7b1a4093 100644
--- a/src/Type/BaseStatusType.php
+++ b/src/Type/BaseStatusType.php
@@ -34,24 +34,40 @@ abstract class BaseStatusType extends AbstractType
      */
     protected $name;
 
-    public function __construct(string $class, string $getter, string $name)
+    /**
+     * @param string $class
+     * @param string $getter
+     * @param string $name
+     */
+    public function __construct($class, $getter, $name)
     {
         $this->class = $class;
         $this->getter = $getter;
         $this->name = $name;
     }
 
-    public function getParent(): string
+    /**
+     * @return string
+     */
+    public function getParent()
     {
         return ChoiceType::class;
     }
 
-    public function getBlockPrefix(): string
+    /**
+     * @return string
+     */
+    public function getBlockPrefix()
     {
         return $this->name;
     }
 
-    public function configureOptions(OptionsResolver $resolver): void
+    public function getName()
+    {
+        return $this->getBlockPrefix();
+    }
+
+    public function configureOptions(OptionsResolver $resolver)
     {
         $resolver->setDefaults([
             'choices' => \call_user_func([$this->class, $this->getter]),
diff --git a/src/Type/BooleanType.php b/src/Type/BooleanType.php
index ae9986eb..a7cc8da6 100644
--- a/src/Type/BooleanType.php
+++ b/src/Type/BooleanType.php
@@ -19,20 +19,23 @@
 use Symfony\Component\Form\FormBuilderInterface;
 use Symfony\Component\OptionsResolver\OptionsResolver;
 
-final class BooleanType extends AbstractType
+/**
+ * @final since sonata-project/form-extensions 0.x
+ */
+class BooleanType extends AbstractType
 {
     public const TYPE_YES = 1;
 
     public const TYPE_NO = 2;
 
-    public function buildForm(FormBuilderInterface $builder, array $options): void
+    public function buildForm(FormBuilderInterface $builder, array $options)
     {
         if ($options['transform']) {
             $builder->addModelTransformer(new BooleanTypeToBooleanTransformer());
         }
     }
 
-    public function configureOptions(OptionsResolver $resolver): void
+    public function configureOptions(OptionsResolver $resolver)
     {
         $resolver->setDefaults([
             'transform' => false,
@@ -45,12 +48,26 @@ public function configureOptions(OptionsResolver $resolver): void
         ]);
     }
 
-    public function getParent(): string
+    /**
+     * @return string
+     */
+    public function getParent()
     {
         return ChoiceType::class;
     }
 
-    public function getBlockPrefix(): string
+    /**
+     * @return string
+     */
+    public function getName()
+    {
+        return $this->getBlockPrefix();
+    }
+
+    /**
+     * @return string
+     */
+    public function getBlockPrefix()
     {
         return 'sonata_type_boolean';
     }
diff --git a/src/Type/CollectionType.php b/src/Type/CollectionType.php
index 56122d89..03b72dab 100644
--- a/src/Type/CollectionType.php
+++ b/src/Type/CollectionType.php
@@ -21,9 +21,12 @@
 use Symfony\Component\Form\FormView;
 use Symfony\Component\OptionsResolver\OptionsResolver;
 
-final class CollectionType extends AbstractType
+/**
+ * @final since sonata-project/form-extensions 0.x
+ */
+class CollectionType extends AbstractType
 {
-    public function buildForm(FormBuilderInterface $builder, array $options): void
+    public function buildForm(FormBuilderInterface $builder, array $options)
     {
         $builder->addEventSubscriber(new ResizeFormListener(
             $options['type'],
@@ -33,13 +36,13 @@ public function buildForm(FormBuilderInterface $builder, array $options): void
         ));
     }
 
-    public function buildView(FormView $view, FormInterface $form, array $options): void
+    public function buildView(FormView $view, FormInterface $form, array $options)
     {
         $view->vars['btn_add'] = $options['btn_add'];
         $view->vars['btn_catalogue'] = $options['btn_catalogue'];
     }
 
-    public function configureOptions(OptionsResolver $resolver): void
+    public function configureOptions(OptionsResolver $resolver)
     {
         $resolver->setDefaults([
             'modifiable' => false,
@@ -51,8 +54,19 @@ public function configureOptions(OptionsResolver $resolver): void
         ]);
     }
 
-    public function getBlockPrefix(): string
+    /**
+     * @return string
+     */
+    public function getBlockPrefix()
     {
         return 'sonata_type_collection';
     }
+
+    /**
+     * @return string
+     */
+    public function getName()
+    {
+        return $this->getBlockPrefix();
+    }
 }
diff --git a/src/Type/DatePickerType.php b/src/Type/DatePickerType.php
index 6ad17ec1..36ffecf3 100644
--- a/src/Type/DatePickerType.php
+++ b/src/Type/DatePickerType.php
@@ -18,10 +18,12 @@
 
 /**
  * @author Hugo Briand <briand@ekino.com>
+ *
+ * @final since sonata-project/form-extensions 0.x
  */
-final class DatePickerType extends BasePickerType
+class DatePickerType extends BasePickerType
 {
-    public function configureOptions(OptionsResolver $resolver): void
+    public function configureOptions(OptionsResolver $resolver)
     {
         $resolver->setDefaults(array_merge($this->getCommonDefaults(), [
             'dp_pick_time' => false,
@@ -31,13 +33,27 @@ public function configureOptions(OptionsResolver $resolver): void
         parent::configureOptions($resolver);
     }
 
-    public function getParent(): string
+    /**
+     * @return string,
+     */
+    public function getParent()
     {
         return DateType::class;
     }
 
-    public function getBlockPrefix(): string
+    /**
+     * @return string
+     */
+    public function getBlockPrefix()
     {
         return 'sonata_type_date_picker';
     }
+
+    /**
+     * @return string
+     */
+    public function getName()
+    {
+        return $this->getBlockPrefix();
+    }
 }
diff --git a/src/Type/DateRangePickerType.php b/src/Type/DateRangePickerType.php
index 424a70e2..ff3a1b51 100644
--- a/src/Type/DateRangePickerType.php
+++ b/src/Type/DateRangePickerType.php
@@ -19,10 +19,12 @@
  * DateRangePickerType.
  *
  * @author Andrej Hudec <pulzarraider@gmail.com>
+ *
+ * @final since sonata-project/form-extensions 0.x
  */
-final class DateRangePickerType extends DateRangeType
+class DateRangePickerType extends DateRangeType
 {
-    public function configureOptions(OptionsResolver $resolver): void
+    public function configureOptions(OptionsResolver $resolver)
     {
         $resolver->setDefaults([
             'field_options' => [],
@@ -34,8 +36,19 @@ public function configureOptions(OptionsResolver $resolver): void
         ]);
     }
 
-    public function getBlockPrefix(): string
+    /**
+     * @return string
+     */
+    public function getBlockPrefix()
     {
         return 'sonata_type_date_range_picker';
     }
+
+    /**
+     * @return string
+     */
+    public function getName()
+    {
+        return $this->getBlockPrefix();
+    }
 }
diff --git a/src/Type/DateRangeType.php b/src/Type/DateRangeType.php
index 6c1197c7..4e0920f4 100644
--- a/src/Type/DateRangeType.php
+++ b/src/Type/DateRangeType.php
@@ -17,10 +17,55 @@
 use Symfony\Component\Form\Extension\Core\Type\DateType;
 use Symfony\Component\Form\FormBuilderInterface;
 use Symfony\Component\OptionsResolver\OptionsResolver;
+use Symfony\Component\Translation\TranslatorInterface as LegacyTranslatorInterface;
+use Symfony\Contracts\Translation\TranslatorInterface;
 
 class DateRangeType extends AbstractType
 {
-    public function buildForm(FormBuilderInterface $builder, array $options): void
+    /**
+     * NEXT_MAJOR: remove this property.
+     *
+     * @var LegacyTranslatorInterface|TranslatorInterface|null
+     *
+     * @deprecated translator property is deprecated since sonata-project/form-extensions 0.x, to be removed in 1.0
+     */
+    protected $translator;
+
+    /**
+     * NEXT_MAJOR: remove this method.
+     *
+     * @deprecated translator dependency is deprecated since sonata-project/form-extensions 0.x, to be removed in 1.0
+     *
+     * @param LegacyTranslatorInterface|TranslatorInterface|null $translator
+     */
+    public function __construct($translator = null)
+    {
+        if (!$translator instanceof LegacyTranslatorInterface && !$translator instanceof TranslatorInterface && null !== $translator) {
+            throw new \InvalidArgumentException(sprintf(
+                'Argument 1 should be an instance of %s or %s or %s',
+                LegacyTranslatorInterface::class,
+                TranslatorInterface::class,
+                'null'
+            ));
+        }
+
+        if (null !== $translator && __CLASS__ !== static::class && DateRangePickerType::class !== static::class) {
+            @trigger_error(
+                sprintf(
+                    'The translator dependency in %s is deprecated since 0.x and will be removed in 1.0. '.
+                    'Please do not call %s with translator argument in %s.',
+                    __CLASS__,
+                    __METHOD__,
+                    static::class
+                ),
+                E_USER_DEPRECATED
+            );
+        }
+
+        $this->translator = $translator;
+    }
+
+    public function buildForm(FormBuilderInterface $builder, array $options)
     {
         $options['field_options_start'] = array_merge(
             [
@@ -50,12 +95,23 @@ public function buildForm(FormBuilderInterface $builder, array $options): void
         );
     }
 
-    public function getBlockPrefix(): string
+    /**
+     * @return string
+     */
+    public function getBlockPrefix()
     {
         return 'sonata_type_date_range';
     }
 
-    public function configureOptions(OptionsResolver $resolver): void
+    /**
+     * @return string
+     */
+    public function getName()
+    {
+        return $this->getBlockPrefix();
+    }
+
+    public function configureOptions(OptionsResolver $resolver)
     {
         $resolver->setDefaults([
             'field_options' => [],
diff --git a/src/Type/DateTimePickerType.php b/src/Type/DateTimePickerType.php
index c84f8cf7..fb824668 100644
--- a/src/Type/DateTimePickerType.php
+++ b/src/Type/DateTimePickerType.php
@@ -18,10 +18,12 @@
 
 /**
  * @author Hugo Briand <briand@ekino.com>
+ *
+ * @final since sonata-project/form-extensions 0.x
  */
-final class DateTimePickerType extends BasePickerType
+class DateTimePickerType extends BasePickerType
 {
-    public function configureOptions(OptionsResolver $resolver): void
+    public function configureOptions(OptionsResolver $resolver)
     {
         $resolver->setDefaults(array_merge($this->getCommonDefaults(), [
             'dp_use_minutes' => true,
@@ -34,13 +36,27 @@ public function configureOptions(OptionsResolver $resolver): void
         parent::configureOptions($resolver);
     }
 
-    public function getParent(): string
+    /**
+     * @return string
+     */
+    public function getParent()
     {
         return DateTimeType::class;
     }
 
-    public function getBlockPrefix(): string
+    /**
+     * @return string
+     */
+    public function getBlockPrefix()
     {
         return 'sonata_type_datetime_picker';
     }
+
+    /**
+     * @return string
+     */
+    public function getName()
+    {
+        return $this->getBlockPrefix();
+    }
 }
diff --git a/src/Type/DateTimeRangePickerType.php b/src/Type/DateTimeRangePickerType.php
index c6f20198..c60a4d51 100644
--- a/src/Type/DateTimeRangePickerType.php
+++ b/src/Type/DateTimeRangePickerType.php
@@ -14,6 +14,8 @@
 namespace Sonata\Form\Type;
 
 use Symfony\Component\OptionsResolver\OptionsResolver;
+use Symfony\Component\Translation\TranslatorInterface as LegacyTranslatorInterface;
+use Symfony\Contracts\Translation\TranslatorInterface;
 
 /**
  * DateTimeRangePickerType.
@@ -22,7 +24,50 @@
  */
 class DateTimeRangePickerType extends DateTimeRangeType
 {
-    public function configureOptions(OptionsResolver $resolver): void
+    /**
+     * NEXT_MAJOR: remove this property.
+     *
+     * @var LegacyTranslatorInterface|TranslatorInterface|null
+     *
+     * @deprecated translator property is deprecated since sonata-project/form-extensions 0.x, to be removed in 1.0
+     */
+    protected $translator;
+
+    /**
+     * NEXT_MAJOR: remove this method.
+     *
+     * @deprecated translator dependency is deprecated since sonata-project/form-extensions 0.x, to be removed in 1.0
+     *
+     * @param LegacyTranslatorInterface|TranslatorInterface|null $translator
+     */
+    public function __construct($translator = null)
+    {
+        if (!$translator instanceof LegacyTranslatorInterface && !$translator instanceof TranslatorInterface && null !== $translator) {
+            throw new \InvalidArgumentException(sprintf(
+                'Argument 1 should be an instance of %s or %s or %s',
+                LegacyTranslatorInterface::class,
+                TranslatorInterface::class,
+                'null'
+            ));
+        }
+
+        if (null !== $translator && __CLASS__ !== static::class && DateRangePickerType::class !== static::class) {
+            @trigger_error(
+                sprintf(
+                    'The translator dependency in %s is deprecated since 0.x and will be removed in 1.0. '.
+                    'Please do not call %s with translator argument in %s.',
+                    __CLASS__,
+                    __METHOD__,
+                    static::class
+                ),
+                E_USER_DEPRECATED
+            );
+        }
+
+        $this->translator = $translator;
+    }
+
+    public function configureOptions(OptionsResolver $resolver)
     {
         $resolver->setDefaults([
             'field_options' => [],
@@ -34,8 +79,19 @@ public function configureOptions(OptionsResolver $resolver): void
         ]);
     }
 
-    public function getBlockPrefix(): string
+    /**
+     * @return string
+     */
+    public function getBlockPrefix()
     {
         return 'sonata_type_datetime_range_picker';
     }
+
+    /**
+     * @return string
+     */
+    public function getName()
+    {
+        return $this->getBlockPrefix();
+    }
 }
diff --git a/src/Type/DateTimeRangeType.php b/src/Type/DateTimeRangeType.php
index 0df96c50..f11b45e6 100644
--- a/src/Type/DateTimeRangeType.php
+++ b/src/Type/DateTimeRangeType.php
@@ -20,7 +20,7 @@
 
 class DateTimeRangeType extends AbstractType
 {
-    public function buildForm(FormBuilderInterface $builder, array $options): void
+    public function buildForm(FormBuilderInterface $builder, array $options)
     {
         $options['field_options_start'] = array_merge(
             [
@@ -50,12 +50,23 @@ public function buildForm(FormBuilderInterface $builder, array $options): void
         );
     }
 
-    public function getBlockPrefix(): string
+    /**
+     * @return string
+     */
+    public function getBlockPrefix()
     {
         return 'sonata_type_datetime_range';
     }
 
-    public function configureOptions(OptionsResolver $resolver): void
+    /**
+     * @return string
+     */
+    public function getName()
+    {
+        return $this->getBlockPrefix();
+    }
+
+    public function configureOptions(OptionsResolver $resolver)
     {
         $resolver->setDefaults([
             'field_options' => [],
diff --git a/src/Type/EqualType.php b/src/Type/EqualType.php
index 0c6d8fa8..cf7c680b 100644
--- a/src/Type/EqualType.php
+++ b/src/Type/EqualType.php
@@ -16,6 +16,8 @@
 use Symfony\Component\Form\AbstractType;
 use Symfony\Component\Form\Extension\Core\Type\ChoiceType;
 use Symfony\Component\OptionsResolver\OptionsResolver;
+use Symfony\Component\Translation\TranslatorInterface as LegacyTranslatorInterface;
+use Symfony\Contracts\Translation\TranslatorInterface;
 
 @trigger_error(
     'The '.__NAMESPACE__.'\EqualType class is deprecated since version 1.2 and will be removed in 2.0.'
@@ -27,14 +29,58 @@
  * NEXT_MAJOR: remove this class.
  *
  * @deprecated since sonata-project/form-extensions 1.2, to be removed with 2.0
+ *
+ * @final since sonata-project/form-extensions 0.x
  */
-final class EqualType extends AbstractType
+class EqualType extends AbstractType
 {
     public const TYPE_IS_EQUAL = 1;
 
     public const TYPE_IS_NOT_EQUAL = 2;
+    /**
+     * NEXT_MAJOR: remove this property.
+     *
+     * @var LegacyTranslatorInterface|TranslatorInterface|null
+     *
+     * @deprecated translator property is deprecated since sonata-project/form-extensions 0.x, to be removed in 1.0
+     */
+    protected $translator;
 
-    public function configureOptions(OptionsResolver $resolver): void
+    /**
+     * NEXT_MAJOR: remove this method.
+     *
+     * @deprecated translator dependency is deprecated since sonata-project/form-extensions 0.x, to be removed in 1.0
+     *
+     * @param LegacyTranslatorInterface|TranslatorInterface|null $translator
+     */
+    public function __construct($translator = null)
+    {
+        if (!$translator instanceof LegacyTranslatorInterface && !$translator instanceof TranslatorInterface && null !== $translator) {
+            throw new \InvalidArgumentException(sprintf(
+                'Argument 1 should be an instance of %s or %s or %s',
+                LegacyTranslatorInterface::class,
+                TranslatorInterface::class,
+                'null'
+            ));
+        }
+
+        if (null !== $translator && __CLASS__ !== static::class && DateRangePickerType::class !== static::class) {
+            @trigger_error(
+                sprintf(
+                    'The translator dependency in %s is deprecated since 0.x and will be removed in 1.0. '.
+                    'Please do not call %s with translator argument in %s.',
+                    __CLASS__,
+                    __METHOD__,
+                    static::class
+                ),
+                E_USER_DEPRECATED
+            );
+        }
+
+        $this->translator = $translator;
+    }
+
+    public function configureOptions(OptionsResolver $resolver)
     {
         $resolver->setDefaults([
             'choice_translation_domain' => 'SonataFormBundle',
@@ -45,13 +91,27 @@ public function configureOptions(OptionsResolver $resolver): void
         ]);
     }
 
-    public function getParent(): string
+    /**
+     * @return string
+     */
+    public function getParent()
     {
         return ChoiceType::class;
     }
 
-    public function getBlockPrefix(): string
+    /**
+     * @return string
+     */
+    public function getBlockPrefix()
     {
         return 'sonata_type_equal';
     }
+
+    /**
+     * @return string
+     */
+    public function getName()
+    {
+        return $this->getBlockPrefix();
+    }
 }
diff --git a/src/Type/ImmutableArrayType.php b/src/Type/ImmutableArrayType.php
index d4b4f530..90fb2b9c 100644
--- a/src/Type/ImmutableArrayType.php
+++ b/src/Type/ImmutableArrayType.php
@@ -17,9 +17,12 @@
 use Symfony\Component\Form\FormBuilderInterface;
 use Symfony\Component\OptionsResolver\OptionsResolver;
 
-final class ImmutableArrayType extends AbstractType
+/**
+ * @final since sonata-project/form-extensions 0.x
+ */
+class ImmutableArrayType extends AbstractType
 {
-    public function buildForm(FormBuilderInterface $builder, array $options): void
+    public function buildForm(FormBuilderInterface $builder, array $options)
     {
         foreach ($options['keys'] as $infos) {
             if ($infos instanceof FormBuilderInterface) {
@@ -44,7 +47,7 @@ public function buildForm(FormBuilderInterface $builder, array $options): void
         }
     }
 
-    public function configureOptions(OptionsResolver $resolver): void
+    public function configureOptions(OptionsResolver $resolver)
     {
         $resolver->setDefaults([
             'keys' => [],
@@ -61,8 +64,19 @@ public function configureOptions(OptionsResolver $resolver): void
         });
     }
 
-    public function getBlockPrefix(): string
+    /**
+     * @return string
+     */
+    public function getBlockPrefix()
     {
         return 'sonata_type_immutable_array';
     }
+
+    /**
+     * @return string
+     */
+    public function getName()
+    {
+        return $this->getBlockPrefix();
+    }
 }
diff --git a/src/Validator/Constraints/InlineConstraint.php b/src/Validator/Constraints/InlineConstraint.php
index 5dbc6d4a..729cccca 100755
--- a/src/Validator/Constraints/InlineConstraint.php
+++ b/src/Validator/Constraints/InlineConstraint.php
@@ -20,8 +20,10 @@
  *
  * @Annotation
  * @Target({"CLASS"})
+ *
+ * @final since sonata-project/form-extensions 0.x
  */
-final class InlineConstraint extends Constraint
+class InlineConstraint extends Constraint
 {
     /**
      * @var mixed
@@ -61,24 +63,27 @@ public function __sleep(): array
         return array_keys(get_object_vars($this));
     }
 
-    public function __wakeup(): void
+    public function __wakeup()
     {
         if (\is_string($this->service) && \is_string($this->method)) {
             return;
         }
 
-        $this->method = static function (): void {
+        $this->method = static function () {
         };
 
         $this->serializingWarning = true;
     }
 
-    public function validatedBy(): string
+    public function validatedBy()
     {
         return 'sonata.form.validator.inline';
     }
 
-    public function isClosure(): bool
+    /**
+     * @return bool
+     */
+    public function isClosure()
     {
         return $this->method instanceof \Closure;
     }
@@ -91,12 +96,18 @@ public function getClosure()
         return $this->method;
     }
 
-    public function getTargets(): string
+    /**
+     * @return mixed
+     */
+    public function getTargets()
     {
         return self::CLASS_CONSTRAINT;
     }
 
-    public function getRequiredOptions(): array
+    /**
+     * @return array
+     */
+    public function getRequiredOptions()
     {
         return [
             'service',
diff --git a/src/Validator/ErrorElement.php b/src/Validator/ErrorElement.php
index b92f7f04..8b7fa51c 100755
--- a/src/Validator/ErrorElement.php
+++ b/src/Validator/ErrorElement.php
@@ -19,54 +19,57 @@
 use Symfony\Component\Validator\ConstraintValidatorFactoryInterface;
 use Symfony\Component\Validator\Context\ExecutionContextInterface;
 
-final class ErrorElement
+/**
+ * @final since sonata-project/form-extensions 0.x
+ */
+class ErrorElement
 {
     private const DEFAULT_TRANSLATION_DOMAIN = 'validators';
 
     /**
      * @var ExecutionContextInterface
      */
-    private $context;
+    protected $context;
 
     /**
      * @var string
      */
-    private $group;
+    protected $group;
 
     /**
      * @var ConstraintValidatorFactoryInterface
      */
-    private $constraintValidatorFactory;
+    protected $constraintValidatorFactory;
 
     /**
      * @var string[]
      */
-    private $stack = [];
+    protected $stack = [];
 
     /**
-     * @var string[]
+     * @var PropertyPath[]
      */
-    private $propertyPaths = [];
+    protected $propertyPaths = [];
 
     /**
      * @var mixed
      */
-    private $subject;
+    protected $subject;
 
     /**
      * @var string
      */
-    private $current = '';
+    protected $current = '';
 
     /**
      * @var string
      */
-    private $basePropertyPath;
+    protected $basePropertyPath;
 
     /**
      * @var array
      */
-    private $errors = [];
+    protected $errors = [];
 
     /**
      * @param mixed  $subject
@@ -76,7 +79,7 @@ public function __construct(
         $subject,
         ConstraintValidatorFactoryInterface $constraintValidatorFactory,
         ExecutionContextInterface $context,
-        ?string $group
+        $group
     ) {
         $this->subject = $subject;
         $this->context = $context;
@@ -86,9 +89,13 @@ public function __construct(
     }
 
     /**
+     * @param string $name
+     *
      * @throws \RuntimeException
+     *
+     * @return ErrorElement
      */
-    public function __call(string $name, array $arguments = []): self
+    public function __call($name, array $arguments = [])
     {
         if ('assert' === substr($name, 0, 6)) {
             $this->validate($this->newConstraint(substr($name, 6), $arguments[0] ?? []));
@@ -99,14 +106,23 @@ public function __call(string $name, array $arguments = []): self
         return $this;
     }
 
-    public function addConstraint(Constraint $constraint): self
+    /**
+     * @return ErrorElement
+     */
+    public function addConstraint(Constraint $constraint)
     {
         $this->validate($constraint);
 
         return $this;
     }
 
-    public function with(string $name, bool $key = false): self
+    /**
+     * @param string $name
+     * @param bool   $key
+     *
+     * @return ErrorElement
+     */
+    public function with($name, $key = false)
     {
         $key = $key ? $name.'.'.$key : $name;
         $this->stack[] = $key;
@@ -120,7 +136,10 @@ public function with(string $name, bool $key = false): self
         return $this;
     }
 
-    public function end(): self
+    /**
+     * @return ErrorElement
+     */
+    public function end()
     {
         array_pop($this->stack);
 
@@ -129,7 +148,10 @@ public function end(): self
         return $this;
     }
 
-    public function getFullPropertyPath(): string
+    /**
+     * @return string
+     */
+    public function getFullPropertyPath()
     {
         if ($this->getCurrentPropertyPath()) {
             return sprintf('%s.%s', $this->basePropertyPath, $this->getCurrentPropertyPath());
@@ -148,11 +170,12 @@ public function getSubject()
 
     /**
      * @param string|array $message
+     * @param array        $parameters
      * @param mixed|null   $value
      *
      * @return ErrorElement
      */
-    public function addViolation($message, array $parameters = [], $value = null, string $translationDomain = self::DEFAULT_TRANSLATION_DOMAIN): self
+    public function addViolation($message, $parameters = [], $value = null, string $translationDomain = self::DEFAULT_TRANSLATION_DOMAIN)
     {
         if (\is_array($message)) {
             $value = $message[2] ?? $value;
@@ -178,12 +201,15 @@ public function addViolation($message, array $parameters = [], $value = null, st
         return $this;
     }
 
-    public function getErrors(): array
+    /**
+     * @return array
+     */
+    public function getErrors()
     {
         return $this->errors;
     }
 
-    private function validate(Constraint $constraint): void
+    protected function validate(Constraint $constraint)
     {
         $this->context->getValidator()
             ->inContext($this->context)
@@ -196,7 +222,7 @@ private function validate(Constraint $constraint): void
      *
      * @return mixed
      */
-    private function getValue()
+    protected function getValue()
     {
         if ('' === $this->current) {
             return $this->subject;
@@ -208,9 +234,11 @@ private function getValue()
     }
 
     /**
+     * @param string $name
+     *
      * @return object
      */
-    private function newConstraint(string $name, array $options = [])
+    protected function newConstraint($name, array $options = [])
     {
         if (false !== strpos($name, '\\') && class_exists($name)) {
             $className = (string) $name;
@@ -221,7 +249,10 @@ private function newConstraint(string $name, array $options = [])
         return new $className($options);
     }
 
-    private function getCurrentPropertyPath(): ?PropertyPath
+    /**
+     * @return PropertyPath|null
+     */
+    protected function getCurrentPropertyPath()
     {
         if (!isset($this->propertyPaths[$this->current])) {
             return null; //global error
diff --git a/src/Validator/InlineValidator.php b/src/Validator/InlineValidator.php
index d04ad89b..311cb3d9 100755
--- a/src/Validator/InlineValidator.php
+++ b/src/Validator/InlineValidator.php
@@ -18,7 +18,10 @@
 use Symfony\Component\Validator\ConstraintValidator;
 use Symfony\Component\Validator\ConstraintValidatorFactoryInterface;
 
-final class InlineValidator extends ConstraintValidator
+/**
+ * @final since sonata-project/form-extensions 0.x
+ */
+class InlineValidator extends ConstraintValidator
 {
     /**
      * @var ContainerInterface
@@ -38,7 +41,7 @@ public function __construct(
         $this->constraintValidatorFactory = $constraintValidatorFactory;
     }
 
-    public function validate($value, Constraint $constraint): void
+    public function validate($value, Constraint $constraint)
     {
         if ($constraint->isClosure()) {
             $function = $constraint->getClosure();
@@ -57,8 +60,10 @@ public function validate($value, Constraint $constraint): void
 
     /**
      * @param mixed $value
+     *
+     * @return ErrorElement
      */
-    protected function getErrorElement($value): ErrorElement
+    protected function getErrorElement($value)
     {
         return new ErrorElement(
             $value,
diff --git a/tests/Type/FormChoiceWidgetTest.php b/tests/Type/FormChoiceWidgetTest.php
index 2ae5ef62..aa48733b 100644
--- a/tests/Type/FormChoiceWidgetTest.php
+++ b/tests/Type/FormChoiceWidgetTest.php
@@ -21,7 +21,7 @@
  */
 class FormChoiceWidgetTest extends AbstractWidgetTestCase
 {
-    public function testLabelRendering(): void
+    public function testLabelRendering()
     {
         $choices = ['some' => 0, 'choices' => 1];