Steve noted that the docs for 4.01 note a new Entitlement format... It
is now JSON based.

However, in the past it was single string, and then with IDM 3.61 there
was a tweak to allow I think | (pipe) separated values, for the SAP UM
fanout drivers.

now we have JSON.

The getEntitlementParameter() function in the LIBAJC ECMA library in
4.01 knows about at least two of those formats and tries both to figure
out which is correct.

HOWEVER, many many drivers in existence rely on the fact that the
payload is a single string, and that you can just take the 'value' of
the entitlement as the value.

For example in the AD driver, for Groups, previously you would have in
the Path.xml something like:
<src>UA</src> (or AF, NRF, RBE and more)
<id>GUID of the group in AD</id>

Now this seems to indicate that the <id> node needs to be JSON, which is
{} enclosed, key value pairs, (surround by quotes, comma delimited)

So it seems like this is a nice extension to make things more powerful,
allow more data to be carried in a single entitlement, but from a
backwards compatability approach, ill advised.

In fact, this seems to me like it would break all sorts of things.

Where is the migration guide explaining how you upgrade existing code,
drivers, etc to use the new Entitlement model.

Just saying you need to run IDM4 Packaged drivers seems a bit extreme to
me, as that implies rip and replace, since doing that throws away all
your customizations.