Пожалуйста, обратитесь к следующему методу:

public Set<LIMSGridCell> getCellsInColumn(String columnIndex){
    Map<String,LIMSGridCell> cellsMap = getCellsMap();
    Set<LIMSGridCell> cells = new HashSet<LIMSGridCell>();
    Set<String> keySet = cellsMap.keySet();
    for(String key: keySet){
      if(key.startsWith(columnIndex)){
        cells.add(cellsMap.get(key));
      }
    }
    return cells;
  }

FindBugs выдают это сообщение:

"Inefficient use of keySet iterator instead of entrySet iterator This method accesses the value of a Map entry, using a key that was retrieved from a keySet iterator. It is more efficient to use an iterator on the entrySet of the map, to avoid the Map.get(key) lookup."