code: public IMetaEntry put(final IMetaEntry pKey, final IMetaEntry pVal) {
          return mMetaMap.put(pKey, pVal);
      }
docs: Putting an entry to the map.
  
  @param pKey
  to be stored.
  @param pVal
  to be stored.
  @return if entry already existing, return that one.
  @see ConcurrentHashMap#put(Object, Object)