void deRegisterQuery(final UserRef userRef, final String queryId) {
        Objects.requireNonNull(userRef);
        Objects.requireNonNull(queryId);
        userQueryToTaskMap.remove(new Key(userRef, queryId));
    }
Marks a query as having been completed
stroom-meta/stroom-meta-impl/src/main/java/stroom/meta/impl/UserQueryRegistry.java