public String
printFlags() {
	StringBuffer sb = new StringBuffer();

	for (int i = 0; i < 16; i++)
		if (validFlag(i) && getFlag(i)) {
			sb.append(Flags.string(i));
			sb.append(" ");
		}
	return sb.toString();
}
Converts the header's flags into a String
src/main/java/core/org/xbill/DNS/Header.java