Add Publication abstract class for inheritance in content models

hibernate-project/src/main/java/com/humanbooster/model/Publication.java

@@ -0,0 +1,65 @@
+package com.humanbooster.model;
+
+import jakarta.persistence.*;
+
+import java.time.LocalDate;
+
+@Entity
+@Inheritance(strategy = InheritanceType.TABLE_PER_CLASS)
+@DiscriminatorColumn
+public abstract class Publication {
+
+    @Id
+    @GeneratedValue(strategy = GenerationType.AUTO)
+    private Long id;
+
+    @Column(nullable = false, length = 200)
+    private String title;
+
+    @Column(nullable = false)
+    private String content;
+
+    @Column(nullable = false)
+    private LocalDate publishDate;
+
+    public Publication() {
+    }
+
+    public Publication(String title, String content, LocalDate publishDate) {
+        this.title = title;
+        this.content = content;
+        this.publishDate = publishDate;
+    }
+
+    public Long getId() {
+        return id;
+    }
+
+    public void setId(Long id) {
+        this.id = id;
+    }
+
+    public String getTitle() {
+        return title;
+    }
+
+    public void setTitle(String title) {
+        this.title = title;
+    }
+
+    public String getContent() {
+        return content;
+    }
+
+    public void setContent(String content) {
+        this.content = content;
+    }
+
+    public LocalDate getPublishDate() {
+        return publishDate;
+    }
+
+    public void setPublishDate(LocalDate publishDate) {
+        this.publishDate = publishDate;
+    }
+}