Add nullability constraints everywhere.

Change-Id: I80577b7784006070f29ce11af4e6fd87c10363bf
diff --git a/src/main/java/eu/mulk/mulkcms2/cms/legacyjournal/LegacyJournalComment.java b/src/main/java/eu/mulk/mulkcms2/cms/legacyjournal/LegacyJournalComment.java
index 06ca820..186d343 100644
--- a/src/main/java/eu/mulk/mulkcms2/cms/legacyjournal/LegacyJournalComment.java
+++ b/src/main/java/eu/mulk/mulkcms2/cms/legacyjournal/LegacyJournalComment.java
@@ -1,6 +1,7 @@
 package eu.mulk.mulkcms2.cms.legacyjournal;
 
 import io.quarkus.hibernate.orm.panache.PanacheEntityBase;
+import javax.annotation.CheckForNull;
 import javax.persistence.Column;
 import javax.persistence.Entity;
 import javax.persistence.FetchType;
@@ -30,15 +31,19 @@
   public String body;
 
   @Column(name = "author", nullable = true, length = -1)
+  @CheckForNull
   public String author;
 
   @Column(name = "email", nullable = true, length = -1)
+  @CheckForNull
   public String email;
 
   @Column(name = "website", nullable = true, length = -1)
+  @CheckForNull
   public String website;
 
   @Column(name = "spam_p", nullable = true)
+  @CheckForNull
   public Boolean spamP;
 
   @Column(name = "submitter_ip", nullable = false, length = -1)