Function as_plain_body 

pub fn as_plain_body(body: &WriteBody) -> ParseMap

The body as plain values, for the checks that run against the raw REST body.

validateRequiredColumns tests object[column].__op == 'Delete' on an undecoded body (SchemaController.js:1340-1342), so a Delete has to be visible as its envelope rather than as a decoded operation. Every other operation is represented by its __op name alone, which is enough for a truthiness test and carries nothing that could be mistaken for a value.