Email subscription

The Flutter Batch Plugin allows you to:

• Add and remove email address from a user profile. The profile will automatically be created if needed.
• Edit a profile's marketing subscription.

In order to set an email address and subscription status on a profile, the creation of a project is required. If no project is set up, any calls made for these actions will be ignored.

Here is how to set an email with a marketing subscription:

// This requires to have a custom user ID registered by calling the `identify` method beforehand.
BatchProfile.instance.newEditor()
    .setEmailAddress("john.doe@batch.com")  // Null to erase. Addresses must be valid.
    .setEmailMarketingSubscription(BatchEmailSubscriptionState.subscribed) // or BatchEmailSubscriptionState.unsubscribed
    .save()