Adding Airplane model

core/src/main/java/cz/muni/fi/pa165/core/data/domain/Airplane.java

+package cz.muni.fi.pa165.core.data.domain;
+
+import cz.muni.fi.pa165.core.data.domain.common.DomainEntity;
+import jakarta.persistence.*;
+import lombok.Data;
+import lombok.NoArgsConstructor;
+
+import java.util.Objects;
+
+@Entity(name = "airplanes")
+@Data
+@NoArgsConstructor
+public class Airplane extends DomainEntity {
+
+    @Column(nullable = false)
+    private String name;
+
+    @Column(nullable = false)
+    private Integer capacity;
+
+    @ManyToOne(fetch = FetchType.LAZY,
+            cascade = {CascadeType.REMOVE, CascadeType.PERSIST, CascadeType.MERGE})
+    private AirplaneType type;
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) {
+            return true;
+        }
+        if (!(o instanceof Airplane airplane)) {
+            return false;
+        }
+        return Objects.equals(getId(), airplane.getId()) && Objects.equals(getName(), airplane.getName()) &&
+                Objects.equals(getCapacity(), airplane.getCapacity()) && Objects.equals(getType(), airplane.getType());
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(getId(), getName(), getCapacity(), getType());
+    }
+}