do not return null

Signed-off-by: Olivier Lamy <[email protected]>

Author: olamy

src/main/java/hudson/tasks/junit/CaseResult.java

@@ -1077,11 +1077,11 @@ void replaceParent(SuiteResult parent) {
     }
 
     public @CheckForNull List<FlakyFailure> getFlakyFailures() {
-        return flakyFailures == null ? null : Collections.unmodifiableList(flakyFailures);
+        return flakyFailures == null ? Collections.emptyList() : Collections.unmodifiableList(flakyFailures);
     }
 
     public @CheckForNull List<RerunFailure> getRerunFailures() {
-        return rerunFailures == null ? null : Collections.unmodifiableList(rerunFailures);
+        return rerunFailures == null ? Collections.emptyList() : Collections.unmodifiableList(rerunFailures);
     }
 
     /**