private void sendSSLShutdown() {
        try {
            ssl.shutdown();
        } catch (IOException ignored) {
            // TODO: The RI ignores close failures in SSLSocket, but need to
            // investigate whether it does for SSLEngine.
        }
    }
Read encrypted data from the OpenSSL network BIO
common/src/main/java/org/conscrypt/ConscryptEngine.java