code: @Override
      public boolean postProcessAfterInstantiation(Object bean, String name) throws BeansException {
          if (bean instanceof TransactionManagerAware) {
              initialize();
              if(transactionManager != null) {
                  TransactionManagerAware tma = (TransactionManagerAware) bean;
                  tma.setTransactionManager(transactionManager);
              }
          }
          return true;
      }
docs: Injects the platform transaction manager into the given bean if
  that bean implements the {@link grails.transaction.TransactionManagerAware} interface.
  @param bean The bean to process.
  @param name The name of the bean.
  @return The bean after the transaction manager has been injected.
  @throws BeansException