I'm not sure what to do here

I think this is right but we need to make 4 of the same method based on whether its cells or not not sure how we would do that.

src/main/java/edu/rpi/legup/puzzle/sudoku/rules/PossibleNumberForRowCaseRule.java

@@ -0,0 +1,96 @@
+package edu.rpi.legup.puzzle.sudoku.rules;
+
+import edu.rpi.legup.model.gameboard.Board;
+import edu.rpi.legup.model.gameboard.CaseBoard;
+import edu.rpi.legup.model.gameboard.PuzzleElement;
+import edu.rpi.legup.model.rules.CaseRule;
+import edu.rpi.legup.model.tree.TreeTransition;
+import edu.rpi.legup.puzzle.sudoku.GroupType;
+import edu.rpi.legup.puzzle.sudoku.SudokuBoard;
+import edu.rpi.legup.puzzle.sudoku.SudokuCell;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class PossibleNumberForRowCaseRule extends CaseRule {
+
+    public PossibleNumberForRowCaseRule() {
+        super("SUDO-CASE-0003", "Possible Numbers for Row",
+                "An empty cell has a limited set of possible numbers that can fill it.",
+                "edu/rpi/legup/images/sudoku/PossibleValues.png");
+    }
+
+    /**
+     * Checks whether the transition logically follows from the parent node using this rule
+     *
+     * @param transition transition to check
+     * @return null if the child node logically follow from the parent node, otherwise error message
+     */
+    @Override
+    public String checkRuleRaw(TreeTransition transition) {
+        return null;
+    }
+
+    /**
+     * Checks whether the child node logically follows from the parent node
+     * at the specific puzzleElement index using this rule
+     *
+     * @param transition    transition to check
+     * @param puzzleElement equivalent puzzleElement
+     * @return null if the child node logically follow from the parent node at the specified puzzleElement,
+     * otherwise error message
+     */
+    @Override
+    public String checkRuleRawAt(TreeTransition transition, PuzzleElement puzzleElement) {
+        return null;
+    }
+
+    @Override
+    public CaseBoard getCaseBoard(Board board) {
+        SudokuBoard sudokuBoard = (SudokuBoard) board.copy();
+        CaseBoard caseBoard = new CaseBoard(sudokuBoard, this);
+        for (PuzzleElement puzzleElement : sudokuBoard.getPuzzleElements()) {
+            if (((SudokuCell) puzzleElement).getData() == 0) {
+                caseBoard.addPickableElement(puzzleElement);
+            }
+        }
+        return caseBoard;
+    }
+    /**
+     * Gets the possible cases at a specific location based on this case rule
+     *
+     * @param board         the current board state
+     * @param puzzleElement equivalent puzzleElement
+     * @return a list of elements the specified could be
+     */
+    @Override
+    public ArrayList<Board> getCases(Board board, PuzzleElement puzzleElement) {
+        return getCases(board, puzzleElement, 1, GroupType.REGION);
+    }
+
+    /**
+     * Gets the possible cases at a specific location based on this case rule
+     *
+     * @param board         the current board state
+     * @param puzzleElement equivalent puzzleElement
+     * @param value         value that the rule will be applied from
+     * @param groupType     group type
+     * @return a list of elements the specified could be
+     */
+    public ArrayList<Board> getCases(Board board, PuzzleElement puzzleElement, int value, GroupType groupType) {
+        ArrayList<Board> cases = new ArrayList<>();
+        SudokuBoard sudokuBoard = (SudokuBoard) board;
+        List<SudokuCell> caseCells = new ArrayList<>();
+        SudokuCell cell = (SudokuCell) puzzleElement;
+        //not sure what we would do here!
+        for (int i = 0; i < 9; i++) {
+            Board newCase = sudokuBoard.copy();
+            PuzzleElement element = newCase.getPuzzleElement(puzzleElement);
+            element.setData(value);
+            newCase.addModifiedData(element);
+            cases.add(newCase);
+        }
+
+        return cases;
+    }
+}