Adde comment to code to improve readability

git-svn-id: https://svn.d4science.research-infrastructures.eu/gcube/trunk/data-publishing/document-store-lib@160445 82a268e6-3cf1-43bd-a215-b396298e98cf

src/main/java/org/gcube/documentstore/persistence/PersistenceBackendFactory.java

@@ -220,7 +220,7 @@ public abstract class PersistenceBackendFactory {
 			persistenceBackends.put(context, target);
 			
 			try {
-				actual.close();
+				actual.close(); // flush is made from close function
 			} catch (Exception e) {
 				logger.error("Error closing {} for context {} which has been substituted reset to {}.",
 						actual.getClass().getSimpleName(), context,