feat: created the abstract class DBRepository

src/main/java/edu/group5/app/model/DBRepository.java

@@ -1,4 +1,40 @@
 package edu.group5.app.model;
 
-public class DBRepository {
+
+import java.util.HashMap;
+
+/**
+ * Abstract base class for repositories that store their data
+ * in a database-related structure.
+ *
+ * <p>
+ *   Extends {@link Repository} and specifies that the content
+ *   is stored as a {@link HashMap}.
+ * </p>
+ */
+public abstract class DBRepository extends Repository {
+  /**
+   * The underlying data structure containing the repository entities.
+   */
+  protected HashMap<Object, Object> content;
+
+  /**
+   * Constructs a DBRepository with the given content.
+   *
+   * @param content the HashMap used to store repository entities
+   */
+  protected DBRepository(HashMap<Object, Object> content) {
+    super(content);
+    this.content = content;
+  }
+
+  /**
+   * Returns the underlying HashMap containing the repository entities.
+   *
+   * @return the repository content as a HashMap
+   */
+  @Override
+  public HashMap<Object, Object> getContent() {
+    return content;
+  }
 }