JoinColumn is missing many properties. This will fix NOT NULL generation for ManyToOne JoinColumns (Apply to AnnotationAssocOnes.java):

--- C:/Users/Sam/AppData/Local/Temp/AnnotationAssocOnes.java-revBASE.svn000.tmp.java Wed Apr 14 22:08:57 2010
+++ C:/Users/Sam/src/ebean/src/main/java/com/avaje/ebeaninternal/server/deploy/parse/AnnotationAssocOnes.java Wed Jun 19 21:24:42 2013
@@ -131,6 +131,9 @@
if (!joinColumn.updatable()){
prop.setDbUpdateable(false);
}
+ if (!joinColumn.nullable()){
+ prop.setNullable(false);
+ }
}

JoinColumns joinColumns = get(prop, JoinColumns.class);