code: protected synchronized void addPrefix(final String prefixString) {
  		if (prefixString != null) {
  			final Set<String> prefixes = getPrefixes();
  			prefixes.add(prefixString);
  			setPrefixes(prefixes);
  		}
  	}
docs: Adds the given prefix to the PrefixConfig.
  
  @param prefixString
  the prefix string