fix: make bytebase_group.members optional and release 3.17.3

[d-bytebase]

Summary

• Flip bytebase_group.members from Required: true to Optional: true so the terraform-plugin-sdk/v2 core schema does not auto-inject MinItems=1 on registration
• Bump VERSION to 3.17.3 and update the tutorial pin

Background

#191 (3.17.2) removed the literal MinItems: 1 and the runtime "at least 1 owner" guard, but a customer reported the plan still fails with:

Error: Insufficient members blocks

Root cause is in the SDK at helper/schema/core_schema.go:211-214:

if s.Required && s.MinItems == 0 {
    // configschema doesn't have a "required" representation for nested
    // blocks, but we can fake it by requiring at least one item.
    ret.MinItems = 1
}

When a nested block is Required: true with MinItems unset, the SDK synthesizes MinItems = 1 on the configschema that Terraform core uses for validation — this runs before any provider code executes, so the runtime guard removal in #191 never gets a chance. Conversely, the same function clears MinItems when Optional: true is set (lines 216-222), so Optional is the documented escape hatch.

The nested member / role attributes stay Required: true — those only apply when a members block is present, which is the desired behavior.

The runtime path already handles an empty set: convertToMemberList type-asserts d.Get("members").(*schema.Set), which returns a non-nil empty set when the block is omitted, so iteration just yields no members.

Test plan

• terraform plan against a bytebase_group resource with no members block succeeds
• terraform plan against a bytebase_group resource with populated members still works as before
• Existing state with members continues to round-trip through terraform refresh

🤖 Generated with Claude Code