allow for empty notification on message
allow for empty notification on message

test plan
 - create a ticket via email connector
 - it should work

fixes KNO-385

Change-Id: I4ea4e60ab5818dde0879ea4d4776520a5b36f10a
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/232711
Reviewed-by: Jonathan Featherstone <c99460343437e667b0585ea68fd7caf7bd0a02ab@instructure.com>
Reviewed-by: Ben Nelson <0e71863cbc50fa6fe1bd2e603850fc266242e29a@instructure.com>
Reviewed-by: Cody Cutrer <c4fe2b1d90ef8f2548c8aeabfa633434316f0305@instructure.com>
Tested-by: Service Cloud Jenkins <9144042a601061f88f1e1d7a1753ea3e2972119d@instructure.com>
QA-Review: Cody Cutrer <c4fe2b1d90ef8f2548c8aeabfa633434316f0305@instructure.com>
Product-Review: Cody Cutrer <c4fe2b1d90ef8f2548c8aeabfa633434316f0305@instructure.com>

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