docs: protected void createInvalidationFile() {
          final String methodName = "createInvalidationFile()";
          final File f = new File(invalidationFileName);
          final CacheOnDisk cod = this;
          traceDebug(methodName, "cacheName=" + this.cacheName + " valueSet=" + cod.valueSet.size());
          AccessController.doPrivileged(new PrivilegedAction() {
              public Object run() {
                  FileOutputStream fos = null;
                  ObjectOutputStream oos = null;
                  try {
                      fos = new FileOutputStream(f);
                      oos = new ObjectOutputStream(fos);
  
                      oos.writeInt(cod.valueSet.size());
                      Iterator it = valueSet.iterator();
                      while (it.hasNext()) {
                          Object entryId = it.next();
                          oos.writeObject(entryId);
                      }
                  } catch (Throwable t1) {
                      com.ibm.ws.ffdc.FFDCFilter.processException(t1, "com.ibm.ws.cache.CacheOnDisk.createInvalidationFile", "1106", cod);
                      traceDebug(methodName, "cacheName=" + cod.cacheName + "\nException: " + ExceptionUtility.getStackTrace(t1));
                  } finally {
                      try {
                          oos.close();
                          fos.close();
                      } catch (Throwable t2) {
                          com.ibm.ws.ffdc.FFDCFilter.processException(t2, "com.ibm.ws.cache.CacheOnDisk.createInvalidationFile", "1113", cod);
                          traceDebug(methodName, "cacheName=" + cod.cacheName + "\nException: " + ExceptionUtility.getStackTrace(t2));
                      }
                  }
  
                  return null;
              }
          });
      }