If an application try to save a document with password field whereas data-system can't encrypt it : Data-system send an error to application and doesn't the document.
In an application try to get a document with password field whereas data-system can't decrypt it : Data-system send the document with encrypt field and add a field '._passwordStillEncrypted' to inform application.
Thank you @poupotte. Can you handle the warning thing in this PR?