Program: 23016
Project: 23016
Buggy source:
private boolean loadSpreadsheet(JsonPrimitive be,boolean needToBuild,FetchedFile igf,Set<String> knownValueSetIds) throws Exception {
  if (be.getAsString().startsWith("String_Node_Str"))   return false;
  FetchedFile f=fetcher.fetchResourceFile(be.getAsString());
  boolean changed=noteFile("String_Node_Str" + be.getAsString(),f);
  if (changed) {
    f.getValuesetsToLoad().clear();
    dlog(LogCategory.PROGRESS,"String_Node_Str" + f.getPath());
    Bundle bnd=new IgSpreadsheetParser(context,execTime,igpkp.getCanonical(),f.getValuesetsToLoad(),first,context.getBinaries().get("String_Node_Str"),knownValueSetIds).parse(f);
    f.setBundle(new FetchedResource());
    f.getBundle().setResource(bnd);
    for (    BundleEntryComponent b : bnd.getEntry()) {
      FetchedResource r=f.addResource();
      r.setResource(b.getResource());
      r.setId(b.getResource().getId());
      r.setElement(convertToElement(r.getResource()));
      r.setTitle(r.getElement().getChildValue("String_Node_Str"));
      igpkp.findConfiguration(f,r);
    }
  }
 else {
    f=altMap.get("String_Node_Str" + be.getAsString());
  }
  for (  String id : f.getValuesetsToLoad().keySet()) {
    if (!knownValueSetIds.contains(id)) {
      String vr=f.getValuesetsToLoad().get(id);
      FetchedFile fv=fetcher.fetchFlexible(vr);
      boolean vrchanged=noteFile("String_Node_Str" + vr,fv);
      if (vrchanged) {
        loadAsElementModel(fv,fv.addResource());
        checkImplicitResourceIdentity(id,fv);
      }
      knownValueSetIds.add(id);
      boolean crchanged=false;
      String cr=vr.replace("String_Node_Str","String_Node_Str");
      if (!cr.equals(vr)) {
        if (fetcher.canFetchFlexible(cr)) {
          fv=fetcher.fetchFlexible(cr);
          crchanged=noteFile("String_Node_Str" + vr,fv);
          if (crchanged) {
            loadAsElementModel(fv,fv.addResource());
            checkImplicitResourceIdentity(id,fv);
          }
        }
      }
      changed=changed || vrchanged || crchanged;
    }
  }
  ImplementationGuideDefinitionPackageComponent pck=publishedIg.getDefinition().addPackage().setName(f.getTitle());
  pck.setId(be.getAsString());
  for (  FetchedResource r : f.getResources()) {
    bndIds.add(r.getElement().fhirType() + "String_Node_Str" + r.getId());
    ImplementationGuideDefinitionResourceComponent res=publishedIg.getDefinition().addResource();
    res.setPackage(pck.getId());
    res.setName(r.getTitle()).setReference(new Reference().setReference(r.getElement().fhirType() + "String_Node_Str" + r.getId()));
  }
  return changed || needToBuild;
}

Fixed version (ground truth):
private boolean loadSpreadsheet(JsonPrimitive be,boolean needToBuild,FetchedFile igf,Set<String> knownValueSetIds) throws Exception {
  if (be.getAsString().startsWith("String_Node_Str"))   return false;
  FetchedFile f=fetcher.fetchResourceFile(be.getAsString());
  boolean changed=noteFile("String_Node_Str" + be.getAsString(),f);
  if (changed) {
    f.getValuesetsToLoad().clear();
    dlog(LogCategory.PROGRESS,"String_Node_Str" + f.getPath());
    Bundle bnd=new IgSpreadsheetParser(context,execTime,igpkp.getCanonical(),f.getValuesetsToLoad(),first,context.getBinaries().get("String_Node_Str"),knownValueSetIds).parse(f);
    f.setBundle(new FetchedResource());
    f.setBundleType(FetchedBundleType.SPREADSHEET);
    f.getBundle().setResource(bnd);
    for (    BundleEntryComponent b : bnd.getEntry()) {
      FetchedResource r=f.addResource();
      r.setResource(b.getResource());
      r.setId(b.getResource().getId());
      r.setElement(convertToElement(r.getResource()));
      r.setTitle(r.getElement().getChildValue("String_Node_Str"));
      igpkp.findConfiguration(f,r);
    }
  }
 else {
    f=altMap.get("String_Node_Str" + be.getAsString());
  }
  for (  String id : f.getValuesetsToLoad().keySet()) {
    if (!knownValueSetIds.contains(id)) {
      String vr=f.getValuesetsToLoad().get(id);
      FetchedFile fv=fetcher.fetchFlexible(vr);
      boolean vrchanged=noteFile("String_Node_Str" + vr,fv);
      if (vrchanged) {
        loadAsElementModel(fv,fv.addResource());
        checkImplicitResourceIdentity(id,fv);
      }
      knownValueSetIds.add(id);
      boolean crchanged=false;
      String cr=vr.replace("String_Node_Str","String_Node_Str");
      if (!cr.equals(vr)) {
        if (fetcher.canFetchFlexible(cr)) {
          fv=fetcher.fetchFlexible(cr);
          crchanged=noteFile("String_Node_Str" + vr,fv);
          if (crchanged) {
            loadAsElementModel(fv,fv.addResource());
            checkImplicitResourceIdentity(id,fv);
          }
        }
      }
      changed=changed || vrchanged || crchanged;
    }
  }
  ImplementationGuideDefinitionPackageComponent pck=publishedIg.getDefinition().addPackage().setName(f.getTitle());
  pck.setId(be.getAsString());
  for (  FetchedResource r : f.getResources()) {
    bndIds.add(r.getElement().fhirType() + "String_Node_Str" + r.getId());
    ImplementationGuideDefinitionResourceComponent res=publishedIg.getDefinition().addResource();
    res.setPackage(pck.getId());
    res.setName(r.getTitle()).setReference(new Reference().setReference(r.getElement().fhirType() + "String_Node_Str" + r.getId()));
  }
  return changed || needToBuild;
}