@Override
  public void connectionClosed(ConnectionEvent event) {
    if (isActive) {
      ManagedConnection conn = (ManagedConnection) event.getSource();
      TransactionManagerImpl transManager = TransactionManagerImpl.getTransactionManager();
      try {
        Transaction txn = transManager.getTransaction();
        if (txn == null) {
          mannPoolCache.returnPooledConnectionToPool(conn);
        }
      } catch (Exception se) {
        String exception =
            "FacetsJCAConnectionManagerImpl::connectionClosed: Exception occurred due to "
                + se.getMessage();
        if (logger.isDebugEnabled()) {
          logger.debug(exception, se);
        }
      }
    }
  }
Callback for Connection Closed.

@param event ConnectionEvent Object.
geode-core/src/main/java/org/apache/geode/internal/datasource/FacetsJCAConnectionManagerImpl.java