Set a default value for envs in Cloud Run Job (GoogleCloudPlatform#13487)

Author: oliver-hohn

mmv1/products/cloudrunv2/Job.yaml

@@ -349,6 +349,10 @@ properties:
                         required: true
                       - name: 'value'
                         type: String
+                        # env is a set.
+                        # The env.value has value "" in Terraform state, but it has value nil in Terraform plan,
+                        # which causes the diffs for unchanged env. default_value: "" is to suppress the diffs.
+                        default_value: ""
                         description: |-
                           Literal value of the environment variable. Defaults to "" and the maximum allowed length is 32768 characters. Variable references are not supported in Cloud Run.
                         # exactly_one_of: