code: public void setDateLastModified(String dateLastModified) {
  
          m_hasDateLastModified = true;
          try {
              if (dateLastModified != null) {
                  TimestampMode timeMode = TimestampMode.getEnum(CmsMacroResolver.stripMacro(dateLastModified));
                  switch (timeMode) {
                      case FILETIME:
                          m_resourceBuilder.setDateLastModified(-1); //Can't get the information right now, must set it afterward.
                          break;
                      case IMPORTTIME:
                          m_resourceBuilder.setDateLastModified(System.currentTimeMillis());
                          break;
                      case VFSTIME:
                      default:
                          m_resourceBuilder.setDateLastModified(convertTimestamp(dateLastModified));
                          break;
                  }
              } else {
                  m_resourceBuilder.setDateLastModified(System.currentTimeMillis());
              }
          } catch (Throwable e) {
              setThrowable(e);
          }
      }
docs: Sets the dateLastModified.<p>
  
  @param dateLastModified the dateLastModified to set
  
  @see #N_DATELASTMODIFIED
  @see #addResourceAttributesRules(Digester, String)