chore[user]: Add JavaDoc to UserRepository

src/main/java/edu/group5/app/model/user/UserRepository.java

@@ -6,7 +6,11 @@
 
 import edu.group5.app.model.DBRepository;
 import edu.group5.app.utils.ParameterValidator;
-
+/**
+ * Repository class for managing User entities. It provides methods to retrieve users,
+ * find users by their unique identifier or email address, and initializes the repository with input data.
+ * The repository uses a HashMap to store User objects for efficient retrieval based on their unique identifier.
+ */
 public class UserRepository extends DBRepository<Integer, User> {
   public final static String ROLE_CUSTOMER = "Customer";
 
@@ -69,6 +73,11 @@ public List<Object[]> export() {
 
   }
 
+  /**
+   * Retrieves a copy of the current users in the repository.
+   * @return a HashMap containing the current users, 
+   * where the key is the user ID and the value is the User object
+   */
   public HashMap<Integer, User> getUsers() {
     return new HashMap<>(content);
   }