Simplify hashcode example

persistence-modules/java-jpa-3/src/main/java/com/baeldung/jpa/equality/EqualByBusinessKey.java

@@ -32,10 +32,7 @@ public class EqualByBusinessKey {
 
     @Override
     public int hashCode() {
-        final int prime = 31;
-        int result = 1;
-        result = prime * result + ((email == null) ? 0 : email.hashCode());
-        return result;
+        return java.util.Objects.hashCode(email);
     }
 
     @Override