refactor: DBRepository to use generics <K, V>

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

@@ -12,18 +12,18 @@
  *   is stored as a {@link HashMap}.
  * </p>
  */
-public abstract class DBRepository extends Repository {
+public abstract class DBRepository<K, V> extends Repository {
   /**
    * The underlying data structure containing the repository entities.
    */
-  protected HashMap<Object, Object> content;
+  protected HashMap<K, V> content;
 
   /**
    * Constructs a DBRepository with the given content.
    *
    * @param content the HashMap used to store repository entities
    */
-  protected DBRepository(HashMap<Object, Object> content) {
+  protected DBRepository(HashMap<K, V> content) {
     super(content);
     this.content = content;
   }
@@ -34,7 +34,7 @@ protected DBRepository(HashMap<Object, Object> content) {
    * @return the repository content as a HashMap
    */
   @Override
-  public HashMap<Object, Object> getContent() {
+  public HashMap<K, V> getContent() {
     return content;
   }
 }