public void updateConfigInstances(final AppConfig appConfig) {
        final int changeCount = refreshGlobalPropYamlOverrides(appConfig);
        if (changeCount > 0) {
            rebuildObjectInstanceMap();
        }
    }
Only for use in testing as this does not wait for DB props to be included
in the effective values
stroom-config/stroom-config-global-impl/src/main/java/stroom/config/global/impl/ConfigMapper.java