blog: Some changes.

Change-Id: Ic2053c65150f3cb9b7e121f4c859a45baf815a4b
diff --git a/blog/src/main/java/eu/mulk/demos/blog/Post.java b/blog/src/main/java/eu/mulk/demos/blog/Post.java
index a12ba70..3ae3fa0 100644
--- a/blog/src/main/java/eu/mulk/demos/blog/Post.java
+++ b/blog/src/main/java/eu/mulk/demos/blog/Post.java
@@ -26,6 +26,15 @@
   @ManyToMany(fetch = FetchType.LAZY)
   public List<Category> categories;
 
-  @OneToMany(fetch = FetchType.LAZY)
+  @OneToMany(fetch = FetchType.LAZY, mappedBy = "post")
   public List<Comment> comments;
+
+  public static Post create(Author author, String title) {
+    var p = new Post();
+    p.title = title;
+    p.publicationDate = Instant.now();
+    p.body = "";
+    p.author = author;
+    return p;
+  }
 }