[Demonstration 1]

[Buggy Method]
public static ImmutableTransactionResponse withTransaction(Transaction transaction) {
    return ImmutableTransactionResponse.builder().amount(transaction.getAmount()).type(transaction.getType()).parentId(Optional.ofNullable(transaction.getParentId())).build();
}

[Buggy Hunk]
.parentId(Optional.ofNullable(transaction.getParentId()))

[Patch]
.parentId(transaction.getParentId())

[Demonstration 2]

[Buggy Method]
private <T extends Piece> boolean opponentHasPieceOffsetFromKing(int colOffset, int rowOffset, Class<T> theClass) {
    try {
        T piece = theClass.cast(board.pieceInSquare(Coordinates.byColumnAndRow(colOffset, kingsPosition.row() + rowOffset)));
        return piece.isNotColorOf(this.player());
    } catch (IllegalCoordinateException | ClassCastException e) {
        return false;
    }
}

[Buggy Hunk]
T piece = theClass.cast(board.pieceInSquare(Coordinates.byColumnAndRow(colOffset, kingsPosition.row()+rowOffset)));

[Patch]
T piece = theClass.cast(board.pieceInSquare(Coordinates.byColumnAndRow(kingsPosition.column()+colOffset, kingsPosition.row()+rowOffset)));