@Override
    public Object getValue(String name) {
        throw new UnsupportedOperationException(
                "All calls to this method should be intercepted by ExternalSession.");
    }
This is returned in the place of a {@link SSLSession} when no TLS connection could be negotiated,
but one was requested from a method that can't throw an exception such as {@link
javax.net.ssl.SSLSocket#getSession()} before {@link javax.net.ssl.SSLSocket#startHandshake()} is
called.
common/src/main/java/org/conscrypt/SSLNullSession.java