docs: private byte[] serializeAppData(BackedSession d2) {
          if (com.ibm.websphere.ras.TraceComponent.isAnyTracingEnabled() && LoggingUtil.SESSION_LOGGER_WAS.isLoggable(Level.FINE)) {
              LoggingUtil.SESSION_LOGGER_WAS.entering(methodClassName, methodNames[SERIALIZE_APP_DATA]);
          }
          // return either the byte array input stream for the app
          // data or a vector of byte array input streams if their is a
          // row for each piece of app data
          ByteArrayOutputStream baos = null;
          ObjectOutputStream oos = null;
          byte[] objbuf = null;
  
          try {
              Map<Object, Object> ht = null;
              if (com.ibm.websphere.ras.TraceComponent.isAnyTracingEnabled() && LoggingUtil.SESSION_LOGGER_WAS.isLoggable(Level.FINE)) {
                  LoggingUtil.SESSION_LOGGER_WAS.logp(Level.FINE, methodClassName, methodNames[SERIALIZE_APP_DATA], "get swappableData and convert to byte array");
              }
              synchronized (d2) {
                  ht = d2.getSwappableData();
              }
  
              // serialize session (app data only) into byte array buffer
              baos = new ByteArrayOutputStream();
              oos = createObjectOutputStream(baos);
              oos.writeObject(ht);
              oos.flush();
              objbuf = baos.toByteArray();
              if (com.ibm.websphere.ras.TraceComponent.isAnyTracingEnabled() && LoggingUtil.SESSION_LOGGER_WAS.isLoggable(Level.FINE)) {
                  LoggingUtil.SESSION_LOGGER_WAS.logp(Level.FINE, methodClassName, methodNames[SERIALIZE_APP_DATA], "success - size of byte array is " + objbuf.length);
              }
  
              oos.close();
              baos.close();
          } catch (ConcurrentModificationException cme) {
              LoggingUtil.SESSION_LOGGER_WAS.logp(Level.INFO, methodClassName, methodNames[SERIALIZE_APP_DATA], "DatabaseHashMap.deferWrite", /* + d2.deferWriteUntilNextTick */
                                                  d2.getId());
          } catch (Exception e) {
              com.ibm.ws.ffdc.FFDCFilter.processException(e, "com.ibm.ws.session.store.db.DatabaseHashMap.commonSetup", "2052", d2);
              LoggingUtil.SESSION_LOGGER_WAS.logp(Level.SEVERE, methodClassName, methodNames[SERIALIZE_APP_DATA], "DatabaseHashMap.commonSetupError");
              LoggingUtil.SESSION_LOGGER_WAS.logp(Level.SEVERE, methodClassName, methodNames[SERIALIZE_APP_DATA], "CommonMessage.exception", e);
          }
          if (com.ibm.websphere.ras.TraceComponent.isAnyTracingEnabled() && LoggingUtil.SESSION_LOGGER_WAS.isLoggable(Level.FINER)) {
              LoggingUtil.SESSION_LOGGER_WAS.exiting(methodClassName, methodNames[SERIALIZE_APP_DATA]);
          }
          return objbuf;
      }