This field can only be specified if logging is enabled for this
backend service. Configures whether all, none or a subset of
optional fields should be added to the reported logs. One of
[INCLUDE_ALL_OPTIONAL, EXCLUDE_ALL_OPTIONAL, CUSTOM]. Default is
EXCLUDE_ALL_OPTIONAL.
Values:
UNDEFINED_OPTIONAL_MODE (0):
A value indicating that the enum field is not
set.
CUSTOM (388595569):
A subset of optional fields.
EXCLUDE_ALL_OPTIONAL (168636099):
None optional fields.
INCLUDE_ALL_OPTIONAL (535606965):
All optional fields.