Fire class is created and DONE for moment

src/main/java/model/Fire.java

+package model;
+
+import util.Position;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+
+public class Fire {
+    private Set<Position> firePositions;
+    private Map<Position, List<Position>> neighbors;
+
+    public Fire(Set<Position> firePositions, Map<Position, List<Position>> neighbors) {
+        this.firePositions = firePositions;
+        this.neighbors = neighbors;
+    }
+
+    public Set<Position> getFirePositions() {
+        return firePositions;
+    }
+
+    public List<Position> spreadFire() {
+        List<Position> modifiedPositions = new ArrayList<>();
+        List<Position> newFirePositions = new ArrayList<>();
+        for (Position fire : firePositions) {
+            newFirePositions.addAll(neighbors.get(fire));
+        }
+        firePositions.addAll(newFirePositions);
+        modifiedPositions.addAll(newFirePositions);
+        return newFirePositions;
+    }
+}