public static boolean isUnsupported(SocketAddress remoteAddress, SessionProtocol protocol) {
        requireNonNull(remoteAddress, "remoteAddress");
        requireNonNull(protocol, "protocol");
        return isUnsupported(key(remoteAddress), protocol);
    }
Returns {@code true} if the specified {@code remoteAddress} is known to have no support for
the specified {@link SessionProtocol}.
core/src/main/java/com/linecorp/armeria/client/SessionProtocolNegotiationCache.java