WAF OpenAPI Error Diagnosis

Answers one precise question: which request parameter of this WAF OpenAPI call is wrong — by name, format, value, or required-ness — relative to the official spec, and what is the corrected call. Works for both WAF generations under the product code waf-openapi:

• WAF 2.0 — api version 2019-09-10 (domain / CNAME onboarding: CreateDomain, DescribeInstanceInfo, ...)
• WAF 3.0 — api version 2021-10-01 (object / template / rule: CreateDefenseRule, DescribeInstance, ...)

The authoritative parameter spec is fetched at diagnosis time from the public OpenAPI metadata endpoint (or aliyun ... --help), never recalled from memory. The core diagnosis is read-only and credential-free.

❗ Hard Constraints (highest priority in this document)