label ignored in nuxeo-operation-button action

Steps to reproduce:

• Create an automation script called startWorkflowForAllPicturesInCampaign
• Create a label called label.actions.startWorkflowForAllPicturesInCampaign in your messages.json
• Create an actions in UI > Actions in View Designer
  • icon: icons:send
  • input: [[document]]
  • label: label.actions.startWorkflowForAllPicturesInCampaign
  • operation: javascript.startWorkflowForAllPicturesInCampaign
  • params: {}
• Deploy your changes
• Go to de view of your document and leave the pointer over your action icon
• The label name is shown, not his value