void shutdown() throws IOException {
        lock.readLock().lock();
        try {
            NativeCrypto.ENGINE_SSL_shutdown(ssl, this, handshakeCallbacks);
        } finally {
            lock.readLock().unlock();
        }
    }
A utility wrapper that abstracts operations on the underlying native SSL instance.
common/src/main/java/org/conscrypt/NativeSsl.java