doSetRollbackOnly method to be implemented in SpringTransactionManager

This issue is raised in continuation with the message posted in ignite user forum (http://apache-ignite-users.70518.x6.nabble.com/SpringTransactionManager-Participating-in-existing-transactions-is-not-supported-td7305.html#a10624). Since the doSetRollBackOnly method is not implemented in SpringTransactionManager, it is not being possible to integrate with spring data's ChainedTransactionManager class. A simple fix (below) would work it seems (however, I did not yet tested with proper rollback test cases though, this implementation at least get rid of the exception chainedtransaction manager raises)

@Override
protected void doSetRollbackOnly(DefaultTransactionStatus status) throws TransactionException

{ Transaction txn = ((Ignite)this.getResourceFactory()).transactions().tx(); if (txn!=null) txn.setRollbackOnly(); }

NOTE: This is the first time I am raising issues in apache. So, apologies if all the details are not proper.