Honor ForceSendFields for query parameters

[renaudhartert-db]

Summary

Query parameters listed in ForceSendFields are now sent on the wire even when they hold a zero value, matching the behavior that already exists for JSON request bodies. This fixes cases like the pipelines Delete API, where setting Cascade to false and adding it to ForceSendFields did not actually send cascade=false on the wire.

Why

Query parameters are serialized from the request struct's url tag by the go-querystring library. That tag uses omitempty, so a zero-valued scalar field (for example a false bool, a 0 int, or an empty string) is dropped from the URL. ForceSendFields was designed to opt out of exactly this behavior, but it was only ever wired into the marshal package, which handles JSON bodies. go-querystring has no knowledge of ForceSendFields, so adding a query field to it had no effect.

(Path parameters are not affected: they are tagged url:"-" and substituted directly into the URL path, so they never flow through this serialization.)

A user reported this for the pipelines Delete API: Cascade defaults to true server-side, so a caller who wants to delete a pipeline without cascading must send cascade=false explicitly. Adding Cascade to ForceSendFields looked like the right way to do that (it is how the same situation is handled for JSON bodies), but the parameter was silently dropped and the server applied its default. This affected every query parameter across all services, not just cascade, including fields nested inside request sub-structs.

How is this tested?

Added two table-driven tests in httpclient/request_test.go. TestMakeQueryStringForceSendFields covers the top-level cases: zero values dropped without ForceSendFields, a false bool sent when forced, non-zero values still sent without forcing, multiple forced fields, forcing not overriding an explicitly set value, and unknown forced field names being ignored. TestMakeQueryStringForceSendFieldsNested covers nested sub-structs: a nested struct honoring its own ForceSendFields, non-nil and nil pointers to nested structs, and doubly nested fields. Also verified end-to-end by calling the real pipelines Delete and iam.CheckPolicy APIs through a fake HTTP transport and confirming the forced zero values appear in the request URL. The full httpclient test suite passes.

[github-actions]

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Inputs:

• PR number: 1728
• Commit SHA: 8cf312138f3f651287b8453a1b7dd1914a6ecba7

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