Fix error on some flux with no expediteur or destinataire

assets/css/admin.css

@@ -2145,4 +2145,13 @@
   -webkit-transition: none;
   -o-transition: unset;
   transition: none;
+}
+/* For fixing bug in admin on select not display => no error on required select fields
+https://github.com/sonata-project/SonataAdminBundle/issues/4022
+*/
+.sonata-ba-content select[tabindex='-1']{
+    display:block !important;
+    width: 0.1px !important;
+    height: 0.1px !important;
+    opacity: 0.01 !important;
 }
\ No newline at end of file

public/build/entrypoints.json

@@ -15,7 +15,7 @@
         "/build/admin.15535d30.js"
       ],
       "css": [
-        "/build/admin.87a6bc21.css"
+        "/build/admin.5dc0eea7.css"
       ]
     }
   }

public/build/manifest.json

 {
   "build/app.css": "/build/app.1fb37df4.css",
   "build/app.js": "/build/app.7a6d9f95.js",
-  "build/admin.css": "/build/admin.87a6bc21.css",
+  "build/admin.css": "/build/admin.5dc0eea7.css",
   "build/admin.js": "/build/admin.15535d30.js",
   "build/runtime.js": "/build/runtime.6ad5c9da.js",
   "build/images/fa-solid-900.svg": "/build/images/fa-solid-900.a838c42a.svg",

src/Entity/Flux.php

@@ -176,11 +176,13 @@ abstract class Flux implements FluxInterface
     protected $data;
 
     /**
+     * @Assert\NotBlank
      * @Groups({"read", "write"})
      */
     protected $expediteur = null;
 
     /**
+     * @Assert\NotBlank
      * @Groups({"read", "write"})
      */
     protected $destinataire = null;