code: public int updateExpirationTime(Object id, long oldExpirationTime, int size, long newExpirationTime, long newValidatorExpirationTime) {
          final String methodName = "updateExpirationTime()";
          int returnCode = NO_EXCEPTION;
          Exception diskException = null;
  
          // update the disk entry header only with new validator expiration time for now.
          if (tc.isDebugEnabled())
              Tr.debug(tc, methodName, "cacheName=" + this.cacheName + " id=" + id + " newValidatorExpirationTime=" + newValidatorExpirationTime);
  
          try {
              rwLock.writeLock().lock();
              object_cache.updateExpirationInHeader(id, newExpirationTime, newValidatorExpirationTime);
          } catch (FileManagerException ex) {
              this.diskCacheException = ex;
              diskException = ex;
              returnCode = DISK_EXCEPTION;
          } catch (HashtableOnDiskException ex) {
              this.diskCacheException = ex;
              diskException = ex;
              returnCode = DISK_EXCEPTION;
          } catch (IOException ex) {
              diskException = ex;
              if (ex.getMessage().equals(DISK_CACHE_IN_GB_OVER_LIMIT_MSG)) {
                  returnCode = DISK_SIZE_OVER_LIMIT_EXCEPTION;
              } else {
                  this.diskCacheException = ex;
                  returnCode = DISK_EXCEPTION;
              }
          } catch (Exception ex) {
              returnCode = OTHER_EXCEPTION;
              diskException = ex;
          } finally {
              rwLock.writeLock().unlock();
              if (returnCode != NO_EXCEPTION && returnCode != NO_EXCEPTION_ENTRY_OVERWRITTEN) {
                  if (tc.isDebugEnabled())
                      Tr.debug(tc, methodName, "cacheName=" + this.cacheName + "\n Exception: " + ExceptionUtility.getStackTrace(diskException));
              }
              if (returnCode == DISK_EXCEPTION || returnCode == OTHER_EXCEPTION) {
                  com.ibm.ws.ffdc.FFDCFilter.processException(diskException, "com.ibm.ws.cache.HTODDynacache.writeCacheEntry", "1239", this);
              }
          }
  
          return returnCode;
      }
docs: Since the real expiration time does not change, the GC will be updated.