-Xoss, -Xsqnopause, -Xoptimize, -Xboundthreads and -Xusealtsigs options were obsoleted in JDK 9 and can be removed from JDK 10.

hotspot/src/share/vm/runtime/arguments.cpp:
    // -Xoss, -Xsqnopause, -Xoptimize, -Xboundthreads, -Xusealtsigs
    } else if (match_option(option, "-Xoss", &tail) ||
               match_option(option, "-Xsqnopause") ||
               match_option(option, "-Xoptimize") ||
               match_option(option, "-Xboundthreads") ||
               match_option(option, "-Xusealtsigs")) {
      // All these options are deprecated in JDK 9 and will be removed in a future release
      char version[256];
      JDK_Version::jdk(9).to_string(version, sizeof(version));
      warning("Ignoring option %s; support was removed in %s", option->optionString, version);