Allowed modifying request headers via pre_create, pre_read, pre_update, or pre_delete custom code

[melinath]

Resolved hashicorp/terraform-provider-google#16331.

The specific resource issue this was blocking (hashicorp/terraform-provider-google#15550) was resolved separately so no changes are needed there.

Given we don't have a clear idea of what features we might need to support in the future, and this does not currently seem to be a common use case, I don't want to implement any kind of special MM field at this time; however, this change would be necessary for any changes to MM fields in the future as well.

Release Note Template for Downstream PRs (will be copied)

[modular-magician]

Hi there, I'm the Modular magician. I've detected the following information about your changes:

Diff report

Your PR generated some diffs in downstreams - here they are.

google provider: Diff ( 400 files changed, 3808 insertions(+), 1 deletion(-))
google-beta provider: Diff ( 458 files changed, 4354 insertions(+), 1 deletion(-))

[modular-magician]

Tests analytics

Total tests: 3569
Passed tests: 3199
Skipped tests: 368
Affected tests: 2

Click here to see the affected service packages

all service packages are affected

Action taken

Found 2 affected test(s) by replaying old test recordings. Starting RECORDING based on the most recent commit. Click here to see the affected tests

TestAccFolderIamPolicy_basic|TestAccSqlUser_postgresIAM

Get to know how VCR tests work

[modular-magician]

$\textcolor{green}{\textsf{Tests passed during RECORDING mode:}}$
TestAccFolderIamPolicy_basic[Debug log]

$\textcolor{green}{\textsf{No issues found for passed tests after REPLAYING rerun.}}$

---

$\textcolor{red}{\textsf{Tests failed during RECORDING mode:}}$
TestAccSqlUser_postgresIAM[Error message] [Debug log]

$\textcolor{red}{\textsf{Please fix these to complete your PR.}}$
View the build log or the debug log for each test

[melinath]

@c2thorn this should be ready for review now; the failing test is unrelated.

[c2thorn]

LGTM, nil check seems to cover all cases

[c2thorn]

FYI @NickElliot some lines added to resource.erb here, so we could close out a bug in time