@OwnerUser public static void startDeviceOwnerPostProvisioning(final Context context, final DevicePolicies policies) {
		startDeviceAndProfileOwnerSharedPostProvisioning(context, policies);
		if (SDK_INT >= O) policies.clearUserRestrictionsIfNeeded(context, UserManager.DISALLOW_ADD_MANAGED_PROFILE);	// Ref: UserRestrictionsUtils.DEFAULT_ENABLED_FOR_DEVICE_OWNERS
	}
All the initializations for mainland as device owner.
engine/src/main/java/com/oasisfeng/island/provisioning/IslandProvisioning.java