Tomcat JDBC Connection Pool interfaces to PostgreSQL...

I am currently working using the Tomcat JDBC Connection Pool (http://tomcat.
apache.org/tomcat-7.0-doc/jdbc-pool.html) which we plan to use in our Java
Web application in order to streamline server resources usage associated to
supporting our PostgreSQL connections (i.e., minimize the number or
connections required).

I am using the following jar files to support my work:

tomcat-jdbc.jar
postgresql-9.4.1208.jre7.jar

Although most of it seems to be working fine so far, I am hitting issues
when I try to "cast" the connection the pool is returning to me (a
ProxyConnection) into either a PGConnection or BaseConnection. I need
those in order to access either of the following PostgreSQL
"advanced/internal" methods:

- addDataType () (PGConnection)
- CopyManager () (BaseConnection).

The Tomcat documentation suggests to extract the native connection by using
the following method:

Connection pgConnection = ((javax.sql.PooledConnection) conn).getConnection
( );

Although this does not fail, using a debugger, I can see that pgConnection
is really an
org.postgresql.jdbc.PgConnection (not an org.postgresql.PGConnection), and
there is not way it seems that I can bridge between the two... even by
using:

pgConnection.unwrap ( PGConnection.class );

I am just wondering if this issue is caused by the fact that I use the

org.apache.tomcat.jdbc.pool.DataSource to instantiate my Connection Pool.

Browsing through the list of choice given to me to determine where
the DataSource class is imported in my Java code, I can see:

javax.sql.DataSource (which I have seen can give one access to PGConnection
from one of my research on the Web - http://stackoverflow
.com/questions/27898632/how-to-cast-jdbc4connection-to-pgconnection),
though if I select it, it tells me that this is an abstract Class that I
cannot instantiate from!

Similarly, another StackOverlflow page (http://stackoverflow
.com/questions/36986653/cast-java-sql-connection-to-pgconnection) suggests
using the following code:

PGConnection pgConnection =
dataSource.getConnection().unwrap(PGConnection.class);

but again, if I try this, I get the following SQLException: "Not a
wrapper of org.postgresql.PGConnection"

(in fact, it turns out that this is exactly the same solution as the
"Tomcat solution" I explained above).

I am running out of alternatives... Any ideas?