check draw

app/src/main/java/chess/model/pieces/Bishop.java

@@ -15,4 +15,9 @@ public class Bishop extends Piece {
 		return visitor.visitPiece(this);
 	}
 
+	@Override
+	public int hashCode() {
+		return 0;
+	}
+
 }

app/src/main/java/chess/model/pieces/King.java

@@ -14,4 +14,9 @@ public class King extends Piece {
 	public <T> T accept(PieceVisitor<T> visitor) {
 		return visitor.visitPiece(this);
 	}
+
+	@Override
+	public int hashCode() {
+		return 1;
+	}
 }

app/src/main/java/chess/model/pieces/Knight.java

@@ -14,4 +14,9 @@ public class Knight extends Piece {
 	public <T> T accept(PieceVisitor<T> visitor) {
 		return visitor.visitPiece(this);
 	}
+
+	@Override
+	public int hashCode() {
+		return 2;
+	}
 }

app/src/main/java/chess/model/pieces/Pawn.java

@@ -18,4 +18,9 @@ public class Pawn extends Piece {
 	public int multiplier() {
 		return getColor() == Color.White ? 1 : -1;
 	}
+
+	@Override
+	public int hashCode() {
+		return 3;
+	}
 }

app/src/main/java/chess/model/pieces/Queen.java

@@ -14,4 +14,9 @@ public class Queen extends Piece {
 	public <T> T accept(PieceVisitor<T> visitor) {
 		return visitor.visitPiece(this);
 	}
+
+	@Override
+	public int hashCode() {
+		return 4;
+	}
 }

app/src/main/java/chess/model/pieces/Rook.java

@@ -14,4 +14,9 @@ public class Rook extends Piece {
 	public <T> T accept(PieceVisitor<T> visitor) {
 		return visitor.visitPiece(this);
 	}
+
+	@Override
+	public int hashCode() {
+		return 5;
+	}
 }