private static @Nullable String getAdjacentSide(final String side, final int rowDelta, final int colDelta) {
    if (rowDelta == -1 && colDelta == 0) {
      return getAdjacentSide(side, BorderLayout.NORTH, BorderLayout.SOUTH);
    }
    if (rowDelta == 1 && colDelta == 0) {
      return getAdjacentSide(side, BorderLayout.SOUTH, BorderLayout.NORTH);
    }
    if (rowDelta == 0 && colDelta == -1) {
      return getAdjacentSide(side, BorderLayout.WEST, BorderLayout.EAST);
    }
    if (rowDelta == 0 && colDelta == 1) {
      return getAdjacentSide(side, BorderLayout.EAST, BorderLayout.WEST);
    }
    return null;
  }
private static @Nullable String getAdjacentSide(final String side, final int rowDelta, final int colDelta)