Unable to access custom user defined type in other schema

As per our requirement we must separate object owner accounts from user accounts.  Therefore all objects required by the application is owned by databse user "b" and the application uses database user "a" to access the database and objects in schema "b".  When the application creates a connection pool it issues the following initialization sql so that it can access all the objects in schema "b": alter session set current_schema = b.
The issue that we're running into is when the application attempts to call a user defined type it attempts to call it by "a.user_defined_type" instead of "b.user_defined_type".  This causes the application to error out because "a.user_defined_type" does not exist.