Add maven compiler

pom.xml

@@ -39,6 +39,12 @@
             <artifactId>postgresql</artifactId>
             <scope>runtime</scope>
         </dependency>
+        <dependency>
+            <groupId>org.apache.maven.plugins</groupId>
+            <artifactId>maven-compiler-plugin</artifactId>
+            <version>3.8.1</version>
+            <type>maven-plugin</type>
+        </dependency>
         <dependency>
             <groupId>org.projectlombok</groupId>
             <artifactId>lombok</artifactId>