code: public void setWaterMarks(String source, long lwmScn, long hwmScn) {
          WaterMarkEntry e = sourceWaterMarkMap.get(source);
          if (e == null) {
              e = new WaterMarkEntry(source);
              sourceWaterMarkMap.put(source, e);
          }
          e.setLWMScn(lwmScn);
          e.setHWMScn(hwmScn);
      }
docs: Sets the water marks of a source.
  
  @param source - the source
  @param lwmScn - the low water mark SCN
  @param hwmScn - the high water mark SCN