class CustomDataSourceResourceConverter extends ResourceConverterImpl<CustomReportDataSource, ClientCustomDataSource> {

    protected Map<String, ResourceReference> convertResourcesToServer(Map<String, ClientReferenceableFile> resources, ToServerConversionOptions options){
        Map<String, ResourceReference> serverResources = null;
        if(resources != null && !resources.isEmpty()){
            serverResources = new HashMap<String, ResourceReference>();
            final ResourceReferenceConverter<ClientReferenceableFile> referenceConverter =
                    resourceReferenceConverterProvider.getConverterForType(ClientReferenceableFile.class);
            for(String key : resources.keySet()){
                serverResources.put(key, referenceConverter.toServer(resources.get(key), options));
            }
        }
        return serverResources;
    }

}