docs/code-samples/serving/hello-world/helloworld-java-spark/service.yaml

apiVersion: serving.knative.dev/v1
kind: Service
metadata:
  name: helloworld-java
  namespace: default
spec:
  template:
    spec:
      containers:
      - image: docker.io/{username}/helloworld-java
        env:  
         - name: TARGET 
           value: "SparkJava Sample v1"