0 implies validation-atmost-once feature is not enabled. It does not imply that connection validation is not enabled. connection validation will work based on its status (true/false).
Probably it was a bug that is fixed in v2.1 ?
I see the following description in the console of v2.1 builds :
"Time-interval within which a connection is validated atmost once. 0 implies it is not enabled."
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