fix spring boot version

build.gradle

@@ -1,6 +1,6 @@
 buildscript {
     ext {
-        versionSpringBoot = '2.1.3.RELEASE'
+        versionSpringBoot = '2.1.6.RELEASE'
     }
 
     repositories {

src/main/java/ru/ulstu/core/model/BaseEntity.java

@@ -7,10 +7,9 @@ import javax.persistence.MappedSuperclass;
 import javax.persistence.Version;
 import javax.validation.constraints.NotNull;
 import java.io.Serializable;
-import java.util.Objects;
 
 @MappedSuperclass
-public abstract class BaseEntity implements Serializable, Comparable {
+public abstract class BaseEntity implements Serializable, Comparable<BaseEntity> {
     @Id
     @GeneratedValue(strategy = GenerationType.TABLE)
     private Integer id;
@@ -42,7 +41,14 @@ public abstract class BaseEntity implements Serializable, Comparable {
             return false;
         }
         BaseEntity other = (BaseEntity) obj;
-        return Objects.equals(id, other.id);
+        if (id == null) {
+            if (other.id != null) {
+                return false;
+            }
+        } else if (!id.equals(other.id)) {
+            return false;
+        }
+        return true;
     }
 
     @Override
@@ -62,8 +68,8 @@ public abstract class BaseEntity implements Serializable, Comparable {
     }
 
     @Override
-    public int compareTo(@NotNull Object o) {
+    public int compareTo(@NotNull BaseEntity o) {
-        return id != null ? id.compareTo(((BaseEntity) o).getId()) : -1;
+        return id != null ? id.compareTo(o.getId()) : -1;
     }
 
     public void reset() {