An enum to be used to mark the essential (for polling) fields in an
API-specific Operation object. A custom Operation object may contain many
different fields, but only few of them are essential to conduct a successful
polling process.
A field in an API-specific (custom) Operation object which carries the same
meaning as google.longrunning.Operation.error.code.
ErrorMessage
A field in an API-specific (custom) Operation object which carries the same
meaning as google.longrunning.Operation.error.message.
Name
A field in an API-specific (custom) Operation object which carries the same
meaning as google.longrunning.Operation.name.
Status
A field in an API-specific (custom) Operation object which carries the same
meaning as google.longrunning.Operation.done. If the annotated field is of
an enum type, annotated_field_name == EnumType.DONE semantics should be
equivalent to Operation.done == true. If the annotated field is of type
boolean, then it should follow the same semantics as Operation.done.
Otherwise, a non-empty value should be treated as Operation.done == true.
