NIFI-7590 In 'CassandraSessionProvider.onDisabled' setting Cassandra-…

…related references properly to null after closing them so that they can be renewed in 'onEnabled' (which creates them only if set to 'null', leaving them closed otherwise).

NIFI-7590 Removed 'CassandraSessionProvider.onStopped'.

This closes #4373.

Signed-off-by: Peter Turcsanyi <turcsanyi@apache.org>

nifi-nar-bundles/nifi-cassandra-bundle/nifi-cassandra-services/src/main/java/org/apache/nifi/service/CassandraSessionProvider.java

@@ -33,7 +33,6 @@
 import org.apache.nifi.annotation.documentation.Tags;
 import org.apache.nifi.annotation.lifecycle.OnDisabled;
 import org.apache.nifi.annotation.lifecycle.OnEnabled;
-import org.apache.nifi.annotation.lifecycle.OnStopped;
 import org.apache.nifi.authentication.exception.ProviderCreationException;
 import org.apache.nifi.cassandra.CassandraSessionProviderService;
 import org.apache.nifi.components.PropertyDescriptor;
@@ -182,19 +181,11 @@ public void onEnabled(final ConfigurationContext context) {
     public void onDisabled(){
         if (cassandraSession != null) {
             cassandraSession.close();
+            cassandraSession = null;
         }
         if (cluster != null) {
             cluster.close();
-        }
-    }
-
-    @OnStopped
-    public void onStopped() {
-        if (cassandraSession != null) {
-            cassandraSession.close();
-        }
-        if (cluster != null) {
-            cluster.close();
+            cluster = null;
         }
     }