docs: protected static String join(String... values) {
  		final StringBuilder buffer = new StringBuilder();
  		for (final String value : values) {
  			if (!Strings.isNullOrEmpty(value)) {
  				if (buffer.length() > 0) {
  					buffer.append(" "); //$NON-NLS-1$
  				}
  				buffer.append(value);
  			}
  		}
  		return buffer.toString();
  	}