[ISSUE #1097]Fix null pointer problem when consumption start time is null

[ssssssnake]

What is the purpose of the change

fix issue #1097

Brief changelog

check if the consume start time is null

Verifying this change

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[coveralls]

Coverage increased (+0.04%) to 50.529% when pulling 5257ca1 on ssssssnake:develop into 44569e4 on apache:develop.