boolean combineIfAdjacentAndSmallEnough(long lowAddr, long highAddr) {
    assert lowAddr <= highAddr;
    int lowSize = OffHeapStoredObject.getSize(lowAddr);
    if (isAdjacent(lowAddr, lowSize, highAddr)) {
      int highSize = OffHeapStoredObject.getSize(highAddr);
      int combinedSize = lowSize + highSize;
      if (isSmallEnough(combinedSize)) {
        // append the highAddr chunk to lowAddr
        OffHeapStoredObject.setSize(lowAddr, combinedSize);
        return true;
      }
    }
    return false;
  }
Return true if the two chunks have been combined into one. If low and high are adjacent to each
other and the combined size is small enough (see isSmallEnough) then low's size will be
increased by the size of high and true will be returned.
geode-core/src/main/java/org/apache/geode/internal/offheap/FreeListManager.java