code: void reserve(String suffix, MetatypeOcd ocd) {
          MetatypeOcd previous = unavailableSuffixes.put(suffix, ocd);
          if (previous != null)
              throw new IllegalArgumentException("aliasSuffix: " + suffix);
      }
docs: Reserve a child alias suffix so that no one else can claim it.
  This method should only be used when an aliasSuffix override is specified in wlp-ra.xml.
  
  @param suffix name of the child alias.
  @param ocd OCD element that is claiming it.
  @throws IllegalArgumentException if another OCD has already reserved the child alias suffix.