code: public Object getPage(long pagePlusOffsetAddress) {
      if (tungstenMemoryMode == MemoryMode.ON_HEAP) {
        final int pageNumber = decodePageNumber(pagePlusOffsetAddress);
        assert (pageNumber >= 0 && pageNumber < PAGE_TABLE_SIZE);
        final MemoryBlock page = pageTable[pageNumber];
        assert (page != null);
        assert (page.getBaseObject() != null);
        return page.getBaseObject();
      } else {
        return null;
      }
    }
docs: Get the page associated with an address encoded by
  {@link TaskMemoryManager#encodePageNumberAndOffset(MemoryBlock, long)}