<sync-adapter xmlns:android="http://schemas.android.com/apk/res/android"
    android:contentAuthority="com.android.calendar"
    android:accountType="@string/account_type"
    android:userVisible="false"
    android:supportsUploading="true"
    android:allowParallelSyncs="true"
    android:isAlwaysSyncable="true" />

<!-- Note:
isAlwaysSyncable = false   Sets isSyncable(contentAuthority) of new Account(type=accountType) to -1
                           → causes a sync with SYNC_EXTRAS_INITIALIZE to be scheduled
                           → that sync is expected to finally set isSyncable to 0 or 1.
isAlwaysSyncable = true    Sets isSyncable(contentAuthority) of new Account(type=accountType) to 1
                           → causes a normal sync (without SYNC_EXTRAS_INITIALIZE) to be scheduled.

There's no possibility to automatically set isSyncable to 0 at account creation.
-->