Forcing cache entry invalidation by a getter after deletion

src/main/java/org/ohdsi/webapi/generationcache/GenerationCacheHelper.java

@@ -56,6 +56,9 @@ public CacheResult computeCacheIfAbsent(CohortDefinition cohortDefinition, Sourc
                     log.info(messagePrefix + " for cohort id = {}. Calculating with design hash = {}", cohortDefinition.getId(), designHash);
                     // Ensure that there are no records in results schema with which we could mess up
                     generationCacheService.removeCache(type, source, designHash);
+                    // the line below forces a cached entry to be really deleted and it is a bit unclear why this line was even present as the cache had to be null anyway
+                    // without it there is a constraint violation exception when there was a cache entry present and the retain covariates option is on  
+                    GenerationCache cachedResultsStillPresent = generationCacheService.getCacheOrEraseInvalid(type, designHash, source.getSourceId());
                     CohortGenerationRequest cohortGenerationRequest = requestBuilder
                             .withExpression(cohortDefinition.getDetails().getExpressionObject())
                             .withSource(source)