Set the default DataSource to be used by the Scheduler. If set,
this will override corresponding settings in Quartz properties.
Note: If this is set, the Quartz settings should not define
a job store "dataSource" to avoid meaningless double configuration.
A Spring-specific subclass of Quartz' JobStoreCMT will be used.
It is therefore strongly recommended to perform all operations on
the Scheduler within Spring-managed (or plain JTA) transactions.
Else, database locking will not properly work and might even break
(e.g. if trying to obtain a lock on Oracle without a transaction).
Supports both transactional and non-transactional DataSource access.
With a non-XA DataSource and local Spring transactions, a single DataSource
argument is sufficient. In case of an XA DataSource and global JTA transactions,
SchedulerFactoryBean's "nonTransactionalDataSource" property should be set,
passing in a non-XA DataSource that will not participate in global transactions.