code: public Guard newGuard(final BooleanSupplier isSatisfied) {
      checkNotNull(isSatisfied, "isSatisfied");
      return new Guard(this) {
        @Override
        public boolean isSatisfied() {
          return isSatisfied.getAsBoolean();
        }
      };
    }
docs: Creates a new {@linkplain Guard guard} for this monitor.
  
  @param isSatisfied the new guard's boolean condition (see {@link Guard#isSatisfied
  isSatisfied()})
  @since 21.0