private void fireChange(final EntityAction action) {
        clearCurrentVolumeList();
        if (entityEventBusProvider != null) {
            try {
                final EntityEventBus entityEventBus = entityEventBusProvider.get();
                if (entityEventBus != null) {
                    entityEventBus.fire(new EntityEvent(EVENT_DOCREF, action));
                }
            } catch (final RuntimeException e) {
                LOGGER.error(e::getMessage, e);
            }
        }
    }
@return An active and non-full volume selected by the configured volume selector
stroom-data/stroom-data-store-impl-fs/src/main/java/stroom/data/store/impl/fs/FsVolumeService.java