allow empty definition #1618

Job	Run time
Build nginx-client-base / build	32s
Build php-fpm-base / build	26s
Build Databox Indexer / build	17s
Build Keycloak / build	27s
Build nginx-cache-purge / build	25s
Build nginx-fpm-base / build	18s
Build nodejs-base / build	16s
Build Matomo NGINX / build	33s
Build Matomo PHP / build	27s
Build Report API / build	22s
Build Expose Client / build	34s
Build Uploader Client / build	18s
Build Dashboard / build	1m 39s
Build Databox Client / build	18s
Build Uploader API / build	1m 11s
Build Configurator / build	47s
Build Notify API / build	1m 8s
Build Databox API / build	1m 57s
Build Expose API / build	1m 21s
Setup stack	13m 12s
	26m 28s

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