The configuration of "option multiple" can be done using an YAML file. This file should be imported into your application configuration.
Imagine configuration like this :
tellaw_sunshine_admin:entities:project:configuration:id:idclass:AppBundle\Entity\Projectattributes:id:label:Idname:label:Nombudget:label:Budgetcompany:label:SociétéfilterAttribute:namelist:title:Title de la page de LISTEdescription:"Descirption courte de la page de liste.<br/> test<br/> test"fields:id:~name:~budget:~company:~search:name:~company:~filters:name:~budget:~company:~
You can set multiple choice field, to adding option multiple on your object field.