optimize code

src/main/java/wtf/beatrice/releasehive/AccountController.java

@@ -1,6 +1,8 @@
 package wtf.beatrice.releasehive;
 
-import org.springframework.web.bind.annotation.*;
+import org.springframework.web.bind.annotation.PostMapping;
+import org.springframework.web.bind.annotation.RequestParam;
+import org.springframework.web.bind.annotation.RestController;
 
 import java.util.UUID;
 

src/main/java/wtf/beatrice/releasehive/HibernateManager.java

@@ -7,7 +7,6 @@ import org.hibernate.cfg.Configuration;
 
 public class HibernateManager
 {
-    private static HibernateManager instance;
     private static Session session;
     private static SessionFactory sessionFactory;
 

src/main/java/wtf/beatrice/releasehive/Main.java

@@ -8,7 +8,6 @@ import org.springframework.boot.SpringApplication;
 import org.springframework.boot.autoconfigure.SpringBootApplication;
 
 import java.util.List;
-import java.util.UUID;
 
 @SpringBootApplication
 public class Main {

src/main/java/wtf/beatrice/releasehive/User.java

@@ -1,7 +1,10 @@
 package wtf.beatrice.releasehive;
 
 
-import javax.persistence.*;
+import javax.persistence.Column;
+import javax.persistence.Entity;
+import javax.persistence.Id;
+import javax.persistence.Table;
 import java.util.UUID;
 
 @Entity