Adds connection unwrapping abilities to CDISEPlatform.java

[ljnelson]

Signed-off-by: Laird Nelson [email protected]

[ljnelson]

This pull request augments the CDISEPlatform class to unwrap connections.

Eclipselink has a bunch of scaffolding to perform various unwrapping-type operations on connections to work around the Oracle driver's (buggy) blind casting of a Connection to an OracleConnection in certain date-and-time-related scenarios. The existing default behavior that Eclipselink implements is itself also flawed: it "unwraps" a Connection by calling connection.getMetaData().getConnection() and assumes that the Connection so returned will be different from the connection whose getMetaData() method was called. (This is actually ruled out by the JDBC contract: connection.getMetaData().getConnection() must return connection; the fact that apparently Eclipselink has encountered drivers for which this is not true indicates a bug in the driver in question, and so the fact that this "workaround" may work for any given driver is actually indicative of a JDBC contract violation in that driver.)

In Helidon 3.0.2 and earlier, we had a similar mistake where a call of connection.getMetaData().getConnection() invoked on a Helidon-proxied Connection would return the underlying, non-proxied Connection. This bug allowed the Oracle driver bug described above to stay hidden. Helidon 3.1.0 fixed this issue, but that uncovered the Oracle driver bug, which will now manifest itself in certain date-and-time situations when used with Eclipselink in Helidon 3.1.0.

To fix all this, this PR simply checks to see if the incoming Connection that should be "unwrapped" is a DelegatingConnection, and, if so, calls super.unwrapConnection(d) with its delegate d.