fixed exams for exam list must be up to date (evict cache)

src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/session/impl/ExamSessionCacheService.java

@@ -110,6 +110,18 @@ public class ExamSessionCacheService {
         return exam;
     }
 
+    @CacheEvict(
+            cacheNames = CACHE_NAME_RUNNING_EXAM,
+            key = "#examId")
+    public Long evict(final Long examId) {
+
+        if (log.isDebugEnabled()) {
+            log.debug("Conditional eviction of running Exam from cache: {}", examId);
+        }
+
+        return examId;
+    }
+
     public boolean isRunning(final Exam exam) {
         if (exam == null) {
             return false;

src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/session/impl/ExamSessionServiceImpl.java

@@ -222,8 +222,10 @@ public class ExamSessionServiceImpl implements ExamSessionService {
 
     @Override
     public Result<Collection<Exam>> getRunningExamsForInstitution(final Long institutionId) {
+        // NOTE: we evict the exam from the cache (if present) to ensure user is seeing always the current state of the Exam
         return this.examDAO.allIdsOfInstitution(institutionId)
                 .map(col -> col.stream()
+                        .map(this.examSessionCacheService::evict)
                         .map(this::getRunningExam)
                         .filter(Result::hasValue)
                         .map(Result::get)