Extend phrase by an example

The following documentation comment has been logged on the website:

Page: https://www.postgresql.org/docs/10/static/rowtypes.html
Description:

Hi.
On the page:
https://www.postgresql.org/docs/10/static/rowtypes.html

>then the same inventory_item composite type shown above would come into
being as a byproduct, and could be used just as above. Note however an
important restriction of the current implementation: since no constraints
are associated with a composite type, the constraints shown in the table
definition do not apply to values of the composite type outside the table.
(A partial workaround is to use domain types as members of composite
types.)

The part:
>(A partial workaround is to use domain types as members of composite
types.)

From here I can understand that workaround is possible.

But what is workaround? and why it is partial?
Would be great to have this description.