diff --git a/.gitignore b/.gitignore
index 708b377..5e5f3b0 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,4 @@
 vendor
 composer.lock
-.phpunit.result.cache
\ No newline at end of file
+.phpunit.result.cache
+.php-cs-fixer.cache
\ No newline at end of file
diff --git a/.php-cs-fixer.php b/.php-cs-fixer.php
new file mode 100644
index 0000000..da272ea
--- /dev/null
+++ b/.php-cs-fixer.php
@@ -0,0 +1,44 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+* This file is part of PHP CS Fixer.
+*
+* (c) Fabien Potencier <fabien@symfony.com>
+*     Dariusz Rumiński <dariusz.ruminski@gmail.com>
+*
+* This source file is subject to the MIT license that is bundled
+* with this source code in the file LICENSE.
+*/
+
+$header = <<<'EOF'
+This file is part of PHP CS Fixer.
+
+(c) Fabien Potencier <fabien@symfony.com>
+Dariusz Rumiński <dariusz.ruminski@gmail.com>
+
+This source file is subject to the MIT license that is bundled
+with this source code in the file LICENSE.
+EOF;
+
+$finder = (new PhpCsFixer\Finder())
+    ->ignoreDotFiles(false)
+    ->ignoreVCSIgnored(true)
+    ->exclude(['dev-tools/phpstan', 'tests/Fixtures'])
+    ->in(__DIR__);
+
+return (new PhpCsFixer\Config())
+    ->setRiskyAllowed(true)
+    ->setRules([
+        '@PHP74Migration' => true,
+        '@PHP74Migration:risky' => true,
+        '@PHPUnit100Migration:risky' => true,
+        '@PhpCsFixer' => true,
+        '@PhpCsFixer:risky' => true,
+        'general_phpdoc_annotation_remove' => ['annotations' => ['expectedDeprecation']], // one should use PHPUnit built-in method instead
+        'header_comment' => ['header' => $header],
+        'modernize_strpos' => true, // needs PHP 8+ or polyfill
+        'no_useless_concat_operator' => false, // TODO switch back on when the `src/Console/Application.php` no longer needs the concat
+    ])
+    ->setFinder($finder);
diff --git a/composer.json b/composer.json
index f186ab4..2a8cf04 100644
--- a/composer.json
+++ b/composer.json
@@ -20,7 +20,7 @@
         "symfony/validator": "^6.3"
     },
     "require-dev": {
-        "friendsofphp/php-cs-fixer": "^2.19",
+        "friendsofphp/php-cs-fixer": "^3.38",
         "phpunit/phpunit": "^9.0"
     },
     "autoload": {
diff --git a/src/Abstracts/Model.php b/src/Abstracts/Model.php
index 96c338d..43ed9d3 100644
--- a/src/Abstracts/Model.php
+++ b/src/Abstracts/Model.php
@@ -1,5 +1,17 @@
 <?php
 
+declare(strict_types=1);
+
+/*
+ * This file is part of PHP CS Fixer.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ * Dariusz Rumiński <dariusz.ruminski@gmail.com>
+ *
+ * This source file is subject to the MIT license that is bundled
+ * with this source code in the file LICENSE.
+ */
+
 namespace Axiostudio\FatturaElettronica\Abstracts;
 
 use Axiostudio\FatturaElettronica\Contracts\Model as ModelInterface;
diff --git a/src/Contracts/Model.php b/src/Contracts/Model.php
index 05c548d..840793d 100644
--- a/src/Contracts/Model.php
+++ b/src/Contracts/Model.php
@@ -1,5 +1,17 @@
 <?php
 
+declare(strict_types=1);
+
+/*
+ * This file is part of PHP CS Fixer.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ * Dariusz Rumiński <dariusz.ruminski@gmail.com>
+ *
+ * This source file is subject to the MIT license that is bundled
+ * with this source code in the file LICENSE.
+ */
+
 namespace Axiostudio\FatturaElettronica\Contracts;
 
 use Symfony\Component\Validator\Mapping\ClassMetadata;
diff --git a/src/FatturaElettronica.php b/src/FatturaElettronica.php
index a6d6c02..f0785d0 100644
--- a/src/FatturaElettronica.php
+++ b/src/FatturaElettronica.php
@@ -1,25 +1,51 @@
 <?php
 
+declare(strict_types=1);
+
+/*
+ * This file is part of PHP CS Fixer.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ * Dariusz Rumiński <dariusz.ruminski@gmail.com>
+ *
+ * This source file is subject to the MIT license that is bundled
+ * with this source code in the file LICENSE.
+ */
+
 namespace Axiostudio\FatturaElettronica;
 
+use Axiostudio\FatturaElettronica\Handlers\Model as ModelHandler;
 use Axiostudio\FatturaElettronica\Handlers\Xml as XmlHandler;
 use Axiostudio\FatturaElettronica\Handlers\XmlDatiBeniServizi as DatiBeniServiziHandler;
-use Axiostudio\FatturaElettronica\Handlers\Model as ModelHandler;
 use Axiostudio\FatturaElettronica\Models\FatturaElettronica as Fattura;
 
 class FatturaElettronica
 {
+    use DatiBeniServiziHandler;
     use ModelHandler;
     use XmlHandler;
-    use DatiBeniServiziHandler;
+
+    public function compose(
+        array $FatturaElettronicaHeader,
+        array $FatturaElettronicaBody,
+        array $DettaglioLinee,
+        array $DatiRiepilogo
+    ): array {
+        return $this->create(
+            $FatturaElettronicaHeader,
+            $FatturaElettronicaBody,
+            $DettaglioLinee,
+            $DatiRiepilogo
+        );
+    }
 
     protected function fileName($header): string
     {
-        $idPaese = (is_array($header[0][0]) && isset($header[0][0][1])) ? $header[0][0][1] : Settings::IdPaeseDefault();
-        $idCodice = (is_array($header[0][0])) ? $header[0][0][0] : $header[0][0];
+        $idPaese = (\is_array($header[0][0]) && isset($header[0][0][1])) ? $header[0][0][1] : Settings::IdPaeseDefault();
+        $idCodice = (\is_array($header[0][0])) ? $header[0][0][0] : $header[0][0];
         $progressivoInvio = $header[0][1];
 
-        return $idPaese . $idCodice . '_' . $progressivoInvio . '.xml';
+        return $idPaese.$idCodice.'_'.$progressivoInvio.'.xml';
     }
 
     protected function fileContent($header, $body): string
@@ -35,27 +61,12 @@ protected function create(
         array $DettaglioLinee,
         array $DatiRiepilogo
     ): array {
-
         $xmlContent = $this->fileContent($FatturaElettronicaHeader, $FatturaElettronicaBody);
         $xmlContent = $this->addDatiBeniServiziToXml($xmlContent, $DettaglioLinee, $DatiRiepilogo);
 
         return [
             'fileContent' => $xmlContent,
-            'fileName' => $this->fileName($FatturaElettronicaHeader)
+            'fileName' => $this->fileName($FatturaElettronicaHeader),
         ];
     }
-
-    public function compose(
-        array $FatturaElettronicaHeader,
-        array $FatturaElettronicaBody,
-        array $DettaglioLinee,
-        array $DatiRiepilogo
-    ): array {
-        return $this->create(
-            $FatturaElettronicaHeader,
-            $FatturaElettronicaBody,
-            $DettaglioLinee,
-            $DatiRiepilogo
-        );
-    }
 }
diff --git a/src/Handlers/Model.php b/src/Handlers/Model.php
index 756925a..bf1b5b1 100644
--- a/src/Handlers/Model.php
+++ b/src/Handlers/Model.php
@@ -1,9 +1,21 @@
 <?php
 
+declare(strict_types=1);
+
+/*
+ * This file is part of PHP CS Fixer.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ * Dariusz Rumiński <dariusz.ruminski@gmail.com>
+ *
+ * This source file is subject to the MIT license that is bundled
+ * with this source code in the file LICENSE.
+ */
+
 namespace Axiostudio\FatturaElettronica\Handlers;
 
-use Symfony\Component\Validator\Validation;
 use Axiostudio\FatturaElettronica\Contracts\Model as ModelInterface;
+use Symfony\Component\Validator\Validation;
 
 trait Model
 {
@@ -11,12 +23,14 @@ public function createModel(ModelInterface $model, bool $toArray = false): array
     {
         $validator = Validation::createValidatorBuilder()
             ->addMethodMapping('loadValidatorMetadata')
-            ->getValidator();
+            ->getValidator()
+        ;
 
         $errors = $validator->validate($model);
 
-        if (count($errors) > 0) {
+        if (\count($errors) > 0) {
             $errorsString = (string) $errors;
+
             throw new \Exception($errorsString);
         }
 
@@ -31,4 +45,4 @@ protected function modelToArray(ModelInterface $model): array
     {
         return json_decode(json_encode($model), true);
     }
-};
+}
diff --git a/src/Handlers/Xml.php b/src/Handlers/Xml.php
index b634d7a..f2ceb7b 100644
--- a/src/Handlers/Xml.php
+++ b/src/Handlers/Xml.php
@@ -1,9 +1,21 @@
 <?php
 
+declare(strict_types=1);
+
+/*
+ * This file is part of PHP CS Fixer.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ * Dariusz Rumiński <dariusz.ruminski@gmail.com>
+ *
+ * This source file is subject to the MIT license that is bundled
+ * with this source code in the file LICENSE.
+ */
+
 namespace Axiostudio\FatturaElettronica\Handlers;
 
-use Spatie\ArrayToXml\ArrayToXml;
 use Axiostudio\FatturaElettronica\Settings;
+use Spatie\ArrayToXml\ArrayToXml;
 
 trait Xml
 {
@@ -14,28 +26,26 @@ public function createXml(array $array): string
         return $this->updateXml($xml);
     }
 
-    protected function updateXml(string $xml): string
+    public function createXmlBlock(array $array): string
     {
-        $xml = str_replace('<?xml version="1.0"?>', Settings::XmlStart(), $xml);
-        $xml = str_replace('<root>', '', $xml);
-        $xml = str_replace('</root>', Settings::XmlEnd(), $xml);
+        $xml = ArrayToXml::convert($array);
 
-        return $xml;
+        return $this->updateXmlBlock($xml);
     }
 
-    public function createXmlBlock(array $array): string
+    protected function updateXml(string $xml): string
     {
-        $xml = ArrayToXml::convert($array);
+        $xml = str_replace('<?xml version="1.0"?>', Settings::XmlStart(), $xml);
+        $xml = str_replace('<root>', '', $xml);
 
-        return $this->updateXmlBlock($xml);
+        return str_replace('</root>', Settings::XmlEnd(), $xml);
     }
 
     protected function updateXmlBlock(string $xml): string
     {
         $xml = str_replace('<?xml version="1.0"?>', '', $xml);
         $xml = str_replace('<root>', '', $xml);
-        $xml = str_replace('</root>', '', $xml);
 
-        return $xml;
+        return str_replace('</root>', '', $xml);
     }
 }
diff --git a/src/Handlers/XmlDatiBeniServizi.php b/src/Handlers/XmlDatiBeniServizi.php
index f9e385b..6cd5036 100644
--- a/src/Handlers/XmlDatiBeniServizi.php
+++ b/src/Handlers/XmlDatiBeniServizi.php
@@ -1,16 +1,26 @@
 <?php
 
+declare(strict_types=1);
+
+/*
+ * This file is part of PHP CS Fixer.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ * Dariusz Rumiński <dariusz.ruminski@gmail.com>
+ *
+ * This source file is subject to the MIT license that is bundled
+ * with this source code in the file LICENSE.
+ */
+
 namespace Axiostudio\FatturaElettronica\Handlers;
 
-use Axiostudio\FatturaElettronica\Handlers\Xml;
-use Axiostudio\FatturaElettronica\Handlers\Model;
 use Axiostudio\FatturaElettronica\Models\DatiRiepilogo;
 use Axiostudio\FatturaElettronica\Models\DettaglioLinee;
 
 trait XmlDatiBeniServizi
 {
-    use Xml;
     use Model;
+    use Xml;
 
     public function addDatiBeniServiziToXml(string $Xml, array $DettaglioLinee = [], array $DatiRiepilogo = []): string
     {
@@ -19,18 +29,16 @@ public function addDatiBeniServiziToXml(string $Xml, array $DettaglioLinee = [],
         foreach ($DettaglioLinee as $numero => $linea) {
             $data = $this->createModel(new DettaglioLinee(...$linea), true);
             $data['NumeroLinea'] = $numero + 1;
-            $DettaglioLineeBlock .= '<DettaglioLinee>' . $this->createXmlBlock($data) . '</DettaglioLinee>';
+            $DettaglioLineeBlock .= '<DettaglioLinee>'.$this->createXmlBlock($data).'</DettaglioLinee>';
         }
 
         $DatiRiepilogoBlock = '';
 
         foreach ($DatiRiepilogo as $dato) {
             $data = $this->createModel(new DatiRiepilogo(...$dato), true);
-            $DatiRiepilogoBlock .= '<DatiRiepilogo>' . $this->createXmlBlock($data) . '</DatiRiepilogo>';
+            $DatiRiepilogoBlock .= '<DatiRiepilogo>'.$this->createXmlBlock($data).'</DatiRiepilogo>';
         }
 
-        $xml = str_replace('<XmlDatiBeniServizi></XmlDatiBeniServizi>', $DettaglioLineeBlock . $DatiRiepilogoBlock, $Xml);
-
-        return $xml;
+        return str_replace('<XmlDatiBeniServizi></XmlDatiBeniServizi>', $DettaglioLineeBlock.$DatiRiepilogoBlock, $Xml);
     }
 }
diff --git a/src/Models/Anagrafica.php b/src/Models/Anagrafica.php
index 59e5853..4c015ea 100644
--- a/src/Models/Anagrafica.php
+++ b/src/Models/Anagrafica.php
@@ -1,5 +1,17 @@
 <?php
 
+declare(strict_types=1);
+
+/*
+ * This file is part of PHP CS Fixer.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ * Dariusz Rumiński <dariusz.ruminski@gmail.com>
+ *
+ * This source file is subject to the MIT license that is bundled
+ * with this source code in the file LICENSE.
+ */
+
 namespace Axiostudio\FatturaElettronica\Models;
 
 use Axiostudio\FatturaElettronica\Abstracts\Model;
@@ -26,8 +38,5 @@ public function __construct(...$args)
         }
     }
 
-    public static function loadValidatorMetadata(ClassMetadata $metadata): void
-    {
-        //
-    }
+    public static function loadValidatorMetadata(ClassMetadata $metadata): void {}
 }
diff --git a/src/Models/CedentePrestatore.php b/src/Models/CedentePrestatore.php
index 307d23a..2a43c53 100644
--- a/src/Models/CedentePrestatore.php
+++ b/src/Models/CedentePrestatore.php
@@ -1,8 +1,19 @@
 <?php
 
+declare(strict_types=1);
+
+/*
+ * This file is part of PHP CS Fixer.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ * Dariusz Rumiński <dariusz.ruminski@gmail.com>
+ *
+ * This source file is subject to the MIT license that is bundled
+ * with this source code in the file LICENSE.
+ */
+
 namespace Axiostudio\FatturaElettronica\Models;
 
-use Axiostudio\FatturaElettronica\Models\Sede;
 use Axiostudio\FatturaElettronica\Abstracts\Model;
 use Symfony\Component\Validator\Mapping\ClassMetadata;
 
@@ -17,8 +28,5 @@ public function __construct(...$args)
         $this->Sede = $this->createModel(new Sede(...$args[1]));
     }
 
-    public static function loadValidatorMetadata(ClassMetadata $metadata): void
-    {
-        //
-    }
+    public static function loadValidatorMetadata(ClassMetadata $metadata): void {}
 }
diff --git a/src/Models/CessionarioCommittente.php b/src/Models/CessionarioCommittente.php
index c2d5d30..4154dc8 100644
--- a/src/Models/CessionarioCommittente.php
+++ b/src/Models/CessionarioCommittente.php
@@ -1,8 +1,19 @@
 <?php
 
+declare(strict_types=1);
+
+/*
+ * This file is part of PHP CS Fixer.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ * Dariusz Rumiński <dariusz.ruminski@gmail.com>
+ *
+ * This source file is subject to the MIT license that is bundled
+ * with this source code in the file LICENSE.
+ */
+
 namespace Axiostudio\FatturaElettronica\Models;
 
-use Axiostudio\FatturaElettronica\Models\Sede;
 use Axiostudio\FatturaElettronica\Abstracts\Model;
 use Symfony\Component\Validator\Mapping\ClassMetadata;
 
@@ -17,8 +28,5 @@ public function __construct(...$args)
         $this->Sede = $this->createModel(new Sede(...$args[1]));
     }
 
-    public static function loadValidatorMetadata(ClassMetadata $metadata): void
-    {
-        //
-    }
+    public static function loadValidatorMetadata(ClassMetadata $metadata): void {}
 }
diff --git a/src/Models/DatiAnagrafici.php b/src/Models/DatiAnagrafici.php
index 1854738..17380a8 100644
--- a/src/Models/DatiAnagrafici.php
+++ b/src/Models/DatiAnagrafici.php
@@ -1,9 +1,21 @@
 <?php
 
+declare(strict_types=1);
+
+/*
+ * This file is part of PHP CS Fixer.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ * Dariusz Rumiński <dariusz.ruminski@gmail.com>
+ *
+ * This source file is subject to the MIT license that is bundled
+ * with this source code in the file LICENSE.
+ */
+
 namespace Axiostudio\FatturaElettronica\Models;
 
-use Axiostudio\FatturaElettronica\Settings;
 use Axiostudio\FatturaElettronica\Abstracts\Model;
+use Axiostudio\FatturaElettronica\Settings;
 use Symfony\Component\Validator\Constraints\Choice;
 use Symfony\Component\Validator\Constraints\Length;
 use Symfony\Component\Validator\Mapping\ClassMetadata;
@@ -17,11 +29,11 @@ class DatiAnagrafici extends Model
 
     public function __construct(...$args)
     {
-        $this->IdFiscaleIVA = is_array($args[0]) ?
+        $this->IdFiscaleIVA = \is_array($args[0]) ?
             $this->createModel(new Id(...$args[0])) :
             $this->createModel(new Id($args[0]));
 
-        $this->Anagrafica = is_array($args[1]) ?
+        $this->Anagrafica = \is_array($args[1]) ?
             $this->createModel(new Anagrafica(...$args[1])) :
             $this->createModel(new Anagrafica($args[1]));
 
diff --git a/src/Models/DatiBeniServizi.php b/src/Models/DatiBeniServizi.php
index d4cf125..01ea996 100644
--- a/src/Models/DatiBeniServizi.php
+++ b/src/Models/DatiBeniServizi.php
@@ -1,5 +1,17 @@
 <?php
 
+declare(strict_types=1);
+
+/*
+ * This file is part of PHP CS Fixer.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ * Dariusz Rumiński <dariusz.ruminski@gmail.com>
+ *
+ * This source file is subject to the MIT license that is bundled
+ * with this source code in the file LICENSE.
+ */
+
 namespace Axiostudio\FatturaElettronica\Models;
 
 use Axiostudio\FatturaElettronica\Abstracts\Model;
@@ -15,8 +27,5 @@ public function __construct(...$args)
         $this->XmlDatiBeniServizi = null;
     }
 
-    public static function loadValidatorMetadata(ClassMetadata $metadata): void
-    {
-        //
-    }
+    public static function loadValidatorMetadata(ClassMetadata $metadata): void {}
 }
diff --git a/src/Models/DatiGenerali.php b/src/Models/DatiGenerali.php
index 0a5a16e..1b9f684 100644
--- a/src/Models/DatiGenerali.php
+++ b/src/Models/DatiGenerali.php
@@ -1,10 +1,21 @@
 <?php
 
+declare(strict_types=1);
+
+/*
+ * This file is part of PHP CS Fixer.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ * Dariusz Rumiński <dariusz.ruminski@gmail.com>
+ *
+ * This source file is subject to the MIT license that is bundled
+ * with this source code in the file LICENSE.
+ */
+
 namespace Axiostudio\FatturaElettronica\Models;
 
 use Axiostudio\FatturaElettronica\Abstracts\Model;
 use Symfony\Component\Validator\Mapping\ClassMetadata;
-use Axiostudio\FatturaElettronica\Models\DatiGeneraliDocumento;
 
 class DatiGenerali extends Model
 {
@@ -15,8 +26,5 @@ public function __construct(...$args)
         $this->DatiGeneraliDocumento = $this->createModel(new DatiGeneraliDocumento(...$args[0]));
     }
 
-    public static function loadValidatorMetadata(ClassMetadata $metadata): void
-    {
-        //
-    }
+    public static function loadValidatorMetadata(ClassMetadata $metadata): void {}
 }
diff --git a/src/Models/DatiGeneraliDocumento.php b/src/Models/DatiGeneraliDocumento.php
index ec93d0c..a1645df 100644
--- a/src/Models/DatiGeneraliDocumento.php
+++ b/src/Models/DatiGeneraliDocumento.php
@@ -1,11 +1,23 @@
 <?php
 
+declare(strict_types=1);
+
+/*
+ * This file is part of PHP CS Fixer.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ * Dariusz Rumiński <dariusz.ruminski@gmail.com>
+ *
+ * This source file is subject to the MIT license that is bundled
+ * with this source code in the file LICENSE.
+ */
+
 namespace Axiostudio\FatturaElettronica\Models;
 
-use Axiostudio\FatturaElettronica\Settings;
-use Symfony\Component\Validator\Constraints\Date;
 use Axiostudio\FatturaElettronica\Abstracts\Model;
+use Axiostudio\FatturaElettronica\Settings;
 use Symfony\Component\Validator\Constraints\Choice;
+use Symfony\Component\Validator\Constraints\Date;
 use Symfony\Component\Validator\Constraints\Length;
 use Symfony\Component\Validator\Mapping\ClassMetadata;
 
diff --git a/src/Models/DatiPagamento.php b/src/Models/DatiPagamento.php
index aaff22c..9c4e543 100644
--- a/src/Models/DatiPagamento.php
+++ b/src/Models/DatiPagamento.php
@@ -1,9 +1,21 @@
 <?php
 
+declare(strict_types=1);
+
+/*
+ * This file is part of PHP CS Fixer.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ * Dariusz Rumiński <dariusz.ruminski@gmail.com>
+ *
+ * This source file is subject to the MIT license that is bundled
+ * with this source code in the file LICENSE.
+ */
+
 namespace Axiostudio\FatturaElettronica\Models;
 
-use Axiostudio\FatturaElettronica\Settings;
 use Axiostudio\FatturaElettronica\Abstracts\Model;
+use Axiostudio\FatturaElettronica\Settings;
 use Symfony\Component\Validator\Constraints\Choice;
 use Symfony\Component\Validator\Mapping\ClassMetadata;
 
diff --git a/src/Models/DatiRiepilogo.php b/src/Models/DatiRiepilogo.php
index 010b0d1..50b5250 100644
--- a/src/Models/DatiRiepilogo.php
+++ b/src/Models/DatiRiepilogo.php
@@ -1,9 +1,21 @@
 <?php
 
+declare(strict_types=1);
+
+/*
+ * This file is part of PHP CS Fixer.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ * Dariusz Rumiński <dariusz.ruminski@gmail.com>
+ *
+ * This source file is subject to the MIT license that is bundled
+ * with this source code in the file LICENSE.
+ */
+
 namespace Axiostudio\FatturaElettronica\Models;
 
-use Axiostudio\FatturaElettronica\Settings;
 use Axiostudio\FatturaElettronica\Abstracts\Model;
+use Axiostudio\FatturaElettronica\Settings;
 use Symfony\Component\Validator\Constraints\Choice;
 use Symfony\Component\Validator\Mapping\ClassMetadata;
 
diff --git a/src/Models/DatiTrasmissione.php b/src/Models/DatiTrasmissione.php
index f087c7e..582adcf 100644
--- a/src/Models/DatiTrasmissione.php
+++ b/src/Models/DatiTrasmissione.php
@@ -1,9 +1,21 @@
 <?php
 
+declare(strict_types=1);
+
+/*
+ * This file is part of PHP CS Fixer.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ * Dariusz Rumiński <dariusz.ruminski@gmail.com>
+ *
+ * This source file is subject to the MIT license that is bundled
+ * with this source code in the file LICENSE.
+ */
+
 namespace Axiostudio\FatturaElettronica\Models;
 
-use Axiostudio\FatturaElettronica\Settings;
 use Axiostudio\FatturaElettronica\Abstracts\Model;
+use Axiostudio\FatturaElettronica\Settings;
 use Symfony\Component\Validator\Constraints\Choice;
 use Symfony\Component\Validator\Constraints\Email;
 use Symfony\Component\Validator\Constraints\Length;
@@ -19,7 +31,7 @@ class DatiTrasmissione extends Model
 
     public function __construct(...$args)
     {
-        $this->IdTrasmittente = is_array($args[0]) ?
+        $this->IdTrasmittente = \is_array($args[0]) ?
             $this->createModel(new Id($args[0][0], $args[0][1])) :
             $this->createModel(new Id($args[0]));
 
diff --git a/src/Models/DettaglioLinee.php b/src/Models/DettaglioLinee.php
index 4f35617..5cedf1b 100644
--- a/src/Models/DettaglioLinee.php
+++ b/src/Models/DettaglioLinee.php
@@ -1,9 +1,21 @@
 <?php
 
+declare(strict_types=1);
+
+/*
+ * This file is part of PHP CS Fixer.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ * Dariusz Rumiński <dariusz.ruminski@gmail.com>
+ *
+ * This source file is subject to the MIT license that is bundled
+ * with this source code in the file LICENSE.
+ */
+
 namespace Axiostudio\FatturaElettronica\Models;
 
-use Axiostudio\FatturaElettronica\Settings;
 use Axiostudio\FatturaElettronica\Abstracts\Model;
+use Axiostudio\FatturaElettronica\Settings;
 use Symfony\Component\Validator\Constraints\Choice;
 use Symfony\Component\Validator\Mapping\ClassMetadata;
 
diff --git a/src/Models/DettaglioPagamento.php b/src/Models/DettaglioPagamento.php
index d15d788..687418f 100644
--- a/src/Models/DettaglioPagamento.php
+++ b/src/Models/DettaglioPagamento.php
@@ -1,5 +1,17 @@
 <?php
 
+declare(strict_types=1);
+
+/*
+ * This file is part of PHP CS Fixer.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ * Dariusz Rumiński <dariusz.ruminski@gmail.com>
+ *
+ * This source file is subject to the MIT license that is bundled
+ * with this source code in the file LICENSE.
+ */
+
 namespace Axiostudio\FatturaElettronica\Models;
 
 use Axiostudio\FatturaElettronica\Abstracts\Model;
diff --git a/src/Models/FatturaElettronica.php b/src/Models/FatturaElettronica.php
index 49344fb..425b28b 100644
--- a/src/Models/FatturaElettronica.php
+++ b/src/Models/FatturaElettronica.php
@@ -1,10 +1,21 @@
 <?php
 
+declare(strict_types=1);
+
+/*
+ * This file is part of PHP CS Fixer.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ * Dariusz Rumiński <dariusz.ruminski@gmail.com>
+ *
+ * This source file is subject to the MIT license that is bundled
+ * with this source code in the file LICENSE.
+ */
+
 namespace Axiostudio\FatturaElettronica\Models;
 
 use Axiostudio\FatturaElettronica\Abstracts\Model;
 use Symfony\Component\Validator\Mapping\ClassMetadata;
-use Axiostudio\FatturaElettronica\Models\FatturaElettronicaBody;
 
 class FatturaElettronica extends Model
 {
@@ -17,8 +28,5 @@ public function __construct(...$args)
         $this->FatturaElettronicaBody = $this->createModel(new FatturaElettronicaBody(...$args[1]));
     }
 
-    public static function loadValidatorMetadata(ClassMetadata $metadata): void
-    {
-        //
-    }
+    public static function loadValidatorMetadata(ClassMetadata $metadata): void {}
 }
diff --git a/src/Models/FatturaElettronicaBody.php b/src/Models/FatturaElettronicaBody.php
index f92f939..392c83f 100644
--- a/src/Models/FatturaElettronicaBody.php
+++ b/src/Models/FatturaElettronicaBody.php
@@ -1,11 +1,21 @@
 <?php
 
+declare(strict_types=1);
+
+/*
+ * This file is part of PHP CS Fixer.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ * Dariusz Rumiński <dariusz.ruminski@gmail.com>
+ *
+ * This source file is subject to the MIT license that is bundled
+ * with this source code in the file LICENSE.
+ */
+
 namespace Axiostudio\FatturaElettronica\Models;
 
 use Axiostudio\FatturaElettronica\Abstracts\Model;
 use Symfony\Component\Validator\Mapping\ClassMetadata;
-use Axiostudio\FatturaElettronica\Models\DatiPagamento;
-use Axiostudio\FatturaElettronica\Models\DatiBeniServizi;
 
 class FatturaElettronicaBody extends Model
 {
@@ -20,8 +30,5 @@ public function __construct(...$args)
         $this->DatiBeniServizi = $this->createModel(new DatiBeniServizi([]));
     }
 
-    public static function loadValidatorMetadata(ClassMetadata $metadata): void
-    {
-        //
-    }
+    public static function loadValidatorMetadata(ClassMetadata $metadata): void {}
 }
diff --git a/src/Models/FatturaElettronicaHeader.php b/src/Models/FatturaElettronicaHeader.php
index 3473846..6d1417d 100644
--- a/src/Models/FatturaElettronicaHeader.php
+++ b/src/Models/FatturaElettronicaHeader.php
@@ -1,5 +1,17 @@
 <?php
 
+declare(strict_types=1);
+
+/*
+ * This file is part of PHP CS Fixer.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ * Dariusz Rumiński <dariusz.ruminski@gmail.com>
+ *
+ * This source file is subject to the MIT license that is bundled
+ * with this source code in the file LICENSE.
+ */
+
 namespace Axiostudio\FatturaElettronica\Models;
 
 use Axiostudio\FatturaElettronica\Abstracts\Model;
@@ -18,8 +30,5 @@ public function __construct(...$args)
         $this->CessionarioCommittente = $this->createModel(new CessionarioCommittente(...$args[2]));
     }
 
-    public static function loadValidatorMetadata(ClassMetadata $metadata): void
-    {
-        //
-    }
+    public static function loadValidatorMetadata(ClassMetadata $metadata): void {}
 }
diff --git a/src/Models/Id.php b/src/Models/Id.php
index 4178b67..cb705dc 100644
--- a/src/Models/Id.php
+++ b/src/Models/Id.php
@@ -1,9 +1,21 @@
 <?php
 
+declare(strict_types=1);
+
+/*
+ * This file is part of PHP CS Fixer.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ * Dariusz Rumiński <dariusz.ruminski@gmail.com>
+ *
+ * This source file is subject to the MIT license that is bundled
+ * with this source code in the file LICENSE.
+ */
+
 namespace Axiostudio\FatturaElettronica\Models;
 
-use Axiostudio\FatturaElettronica\Settings;
 use Axiostudio\FatturaElettronica\Abstracts\Model;
+use Axiostudio\FatturaElettronica\Settings;
 use Symfony\Component\Validator\Constraints\Length;
 use Symfony\Component\Validator\Mapping\ClassMetadata;
 
diff --git a/src/Models/Sede.php b/src/Models/Sede.php
index 8864d31..8b90918 100644
--- a/src/Models/Sede.php
+++ b/src/Models/Sede.php
@@ -1,5 +1,17 @@
 <?php
 
+declare(strict_types=1);
+
+/*
+ * This file is part of PHP CS Fixer.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ * Dariusz Rumiński <dariusz.ruminski@gmail.com>
+ *
+ * This source file is subject to the MIT license that is bundled
+ * with this source code in the file LICENSE.
+ */
+
 namespace Axiostudio\FatturaElettronica\Models;
 
 use Axiostudio\FatturaElettronica\Abstracts\Model;
diff --git a/src/Settings.php b/src/Settings.php
index 5565d9c..83f7551 100644
--- a/src/Settings.php
+++ b/src/Settings.php
@@ -1,5 +1,17 @@
 <?php
 
+declare(strict_types=1);
+
+/*
+ * This file is part of PHP CS Fixer.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ * Dariusz Rumiński <dariusz.ruminski@gmail.com>
+ *
+ * This source file is subject to the MIT license that is bundled
+ * with this source code in the file LICENSE.
+ */
+
 namespace Axiostudio\FatturaElettronica;
 
 class Settings