Fix UrkundSubmissionRepositoryTest

It previously did not populate all the required attributes that were checked using NOT NULL constraints in the migration scripts but were not present in the Hibernate generated DDL for HSQLDB.

core/src/test/java/se/su/dsv/scipro/plagiarism/urkund/UrkundSubmissionRepositoryTest.java

@@ -13,6 +13,7 @@ import org.hamcrest.TypeSafeMatcher;
 import org.junit.jupiter.api.Test;
 import se.su.dsv.scipro.file.FileDescription;
 import se.su.dsv.scipro.file.FileReference;
+import se.su.dsv.scipro.system.User;
 import se.su.dsv.scipro.test.SpringTest;
 
 public class UrkundSubmissionRepositoryTest extends SpringTest {
@@ -23,11 +24,14 @@ public class UrkundSubmissionRepositoryTest extends SpringTest {
     @Test
     public void save() {
         final Instant submitted = Instant.now();
+        User bob = User.builder().firstName("Bob").lastName("Sponge").emailAddress("bob@example.com").build();
+        save(bob);
         final UrkundSubmission submission = new UrkundSubmission();
         submission.setState(UrkundSubmission.State.SUBMITTED);
         submission.setMessage("Hi");
         submission.setSubmitted(submitted);
         submission.setNextPoll(submitted);
+        submission.setReceiver(bob);
         final FileDescription file = save(new FileDescription());
         final FileReference fileReference = new FileReference();
         fileReference.setFileDescription(file);