code: func ApplyDiff(base cty.Value, d *terraform.InstanceDiff, schema *configschema.Block) (cty.Value, error) {
  	return d.ApplyToValue(base, schema)
  }
docs: // ApplyDiff takes a cty.Value state and applies a terraform.InstanceDiff to
  // get a new cty.Value state. This is used to convert the diff returned from
  // the legacy provider Diff method to the state required for the new
  // PlanResourceChange method.