The birthday associated with the customer profile, in RFC 3339 format. The year is optional. The timezone and time are not allowed.
For example, 0000-09-21T00:00:00-00:00
represents a birthday on September 21 and 1998-09-21T00:00:00-00:00
represents a birthday on September 21, 1998.
You can also specify this value in YYYY-MM-DD
format.