fix(fixtures): ensure bidirectional linkage between DatasetVersion and TermsOfUseAndAccess in MinimalPopulator

Author: poikilotherm

src/test/java/edu/harvard/iq/dataverse/util/testing/fixtures/MinimalPopulator.java

@@ -50,7 +50,13 @@ public void populateDatasetVersion(DatasetVersion version, BuildContext context)
         version.setVersionNote("fixture-version");
         version.setCreateTime(now);
         version.setLastUpdateTime(now);
-        version.setTermsOfUseAndAccess(new TermsOfUseAndAccess());
+        
+        // TermsOfUseAndAccess and DatasetVersion are mutually linked via a OneToOne.
+        // The validator reads datasetVersion from the terms object, so both sides
+        // must be wired before the entity graph is persisted.
+        TermsOfUseAndAccess terms = new TermsOfUseAndAccess();
+        terms.setDatasetVersion(version);
+        version.setTermsOfUseAndAccess(terms);
     }
 
     /**