code: private void readLastScanFile() {
          final String methodName = "readLastScanFile()";
          final File f = new File(lastScanFileName);
          traceDebug(methodName, "cacheName=" + this.cacheName);
          if (f.exists()) {
              final CacheOnDisk cod = this;
              AccessController.doPrivileged(new PrivilegedAction() {
                  @Override
                  public Object run() {
                      FileInputStream fis = null;
                      ObjectInputStream ois = null;
                      try {
                          fis = new FileInputStream(f);
                          ois = new ObjectInputStream(fis);
                          cod.lastScanTime = ois.readLong();
                      } catch (Throwable t) {
                          com.ibm.ws.ffdc.FFDCFilter.processException(t, "com.ibm.ws.cache.CacheOnDisk.readLastScanFile", "611", cod);
                          traceDebug(methodName, "cacheName=" + cod.cacheName + "\nException: " + ExceptionUtility.getStackTrace(t));
                      } finally {
                          try {
                              if (ois != null) {
                                  ois.close();
                              }
                              if (fis != null) {
                                  fis.close();
                              }
                          } catch (Throwable t) {
                              com.ibm.ws.ffdc.FFDCFilter.processException(t, "com.ibm.ws.cache.CacheOnDisk.readLastScanFile", "622", cod);
                              traceDebug(methodName, "cacheName=" + cod.cacheName + "\nException: " + ExceptionUtility.getStackTrace(t));
                          }
                      }
                      return null;
                  }
              });
          }
      }
docs: Call this method to read the timestamp of the last scan in Last Scan file.