Use Connection.isValid() in org.jboss.jca.adapters.jdbc.extensions.oracle.OracleValidConnectionChecker

Current Oracle drivers implement Connection.isValid() and this is the preferred mechanism (rather than pingDatabase). To benefit existing applications using current drivers it would be helpful if the existing OracleValidConnectionChecker were updated to leverage the preferred validation mechanism. Perhaps the pingDatabase-based implementation could be moved to a legacy package?