@Override
  public void destroy() throws ResourceException {
    invalidateAndRemoveConnections();
    transactionManager = null;
    cache = null;
    localTransaction = null;
    listeners.clear();
  }
Invalidate and remove the {@link GFConnectionImpl} from the connections collection.
The approach to use removeAll instead of Iterator.remove is purely a performance optimization
to avoid creating all the intermediary collections that will be created when using the single
remove operation.
geode-core/src/jca/java/org/apache/geode/internal/ra/spi/JCAManagedConnection.java