boolean canConnect(Node node, long now) {
        return connectionStates.canConnect(node.idString(), now);
    }
Begin connecting to the given node, return true if we are already connected and ready to send to that node.

@param node The node to check
@param now The current timestamp
@return True if we are ready to send to the given node
clients/src/main/java/org/apache/kafka/clients/NetworkClient.java