public void collect(Heap heap) {
collect(heap, null);
}
public void collect(Heap heap, InstanceCallback callback) {
JavaClass string = heap.getJavaClassByName("java.lang.String");
for(Instance i : heap.getAllInstances()) {
if (i.getJavaClass() == string) {
strings.set(i.getInstanceId(), true);
for(FieldValue fv: i.getFieldValues()) {
if ("value".equals(fv.getField().getName())) {