public static @Nullable RadComponent getComponentAtGrid(RadContainer container, final int row, final int column) {
    // If the target cell is not empty does not allow drop.
    for(int i=0; i<container.getComponentCount(); i++){
      final RadComponent component = container.getComponent(i);
      if (component.isDragging()) {
        continue;
      }
      final GridConstraints constraints=component.getConstraints();
      if(
        constraints.getRow() <= row && row < constraints.getRow()+constraints.getRowSpan() &&
        constraints.getColumn() <= column && column < constraints.getColumn()+constraints.getColSpan()
      ){
        return component;
      }
    }
    return null;
  }
public static @Nullable RadComponent getComponentAtGrid(RadContainer container, final int row, final int column)