fix(schema): resolve configuration drift in device group, alert rule, escalation chain

[ryanmat]

Summary

• Add DiffSuppressFunc to NameAndValue value field to handle LM API masking sensitive properties as ********** — eliminates perpetual diff on password/token properties
• Add Computed: true to device group extra field so API-returned cloud account data does not cause perpetual deletion plans
• Add Computed: true to custom_properties in device_group, device, collector, and collector_group resource schemas so server-injected properties do not cause ordering drift
• Normalize nil escalating_chain to empty map in alert rule state to prevent null vs empty map drift on every plan
• Add bounds check on escalation chain stages to prevent index out-of-bounds panic when Stages slice is empty

Fixes #53, #57, #85, #92, #115, #124

Files Changed

• logicmonitor/schemata/name_and_value_schema.go — DiffSuppressFunc on value field
• logicmonitor/schemata/device_group_schema.go — Computed on extra + custom_properties
• logicmonitor/schemata/device_schema.go — Computed on custom_properties
• logicmonitor/schemata/collector_schema.go — Computed on custom_properties
• logicmonitor/schemata/collector_group_schema.go — Computed on custom_properties
• logicmonitor/schemata/alert_rule_schema.go — nil guard on escalating_chain
• logicmonitor/schemata/chain_schema.go — bounds check on Stages
• logicmonitor/schemata/drift_fixes_test.go — unit tests (10 tests, 17 cases)

Testing

• Unit tests: go test ./logicmonitor/schemata/ -v (all 17 cases pass)
• Live portal validation: tested against a live LogicMonitor portal (lmryanmatuszewski) using Terraform 1.14.8 with dev_overrides
  • Device group 1870: terraform import + terraform plan = 0 changes (extra block and custom_properties clean)
  • Alert rule 3: terraform import + terraform plan = 0 changes (escalating_chain nil drift resolved)
  • Plan status: "no_changes" confirmed via structured JSON output

Cross-cutting root cause

The provider is auto-generated by go-swagger. The generated schema code lacks:

1. DiffSuppressFunc for masked/sensitive values
2. Computed: true on server-managed fields
3. Nil-to-empty-map normalization for TypeMap fields
4. Bounds checking on nested slice access

These are common patterns in hand-maintained Terraform providers that the generator does not produce.