private void
checkDone() {
	if (done && result != -1)
		return;
	StringBuffer sb = new StringBuffer("Lookup of " + name + " ");
	if (dclass != DClass.IN)
		sb.append(DClass.string(dclass) + " ");
	sb.append(Type.string(type) + " isn't done");
	throw new IllegalStateException(sb.toString());
}
Performs the lookup, using the specified Cache, Resolver, and search path.
@return The answers, or null if none are found.
src/main/java/core/org/xbill/DNS/Lookup.java