The `simple-ecs` module is using a singleton EndpoingcostserviceProvider object to support ECS query and maintain the query state. See `alto-basic/simple-ecs/impl/src/main/java/org/opendaylight/alto/basic/endpointcostservice/impl/EndpoingcostserviceProvider.java:90`.

It should be fixed by initiating a new state object maintenance object for each query.