Update assign_public_ip field when importing

This addresses github issue #593

Author: alexng-canuck

CHANGELOG.md

@@ -1,7 +1,8 @@
 ## 3.1.2 (Unreleased)
 
 ### Fixed
-- Fixed bug with specifying lifecycle state in container enginge cluster datasource. Issue [#600](https://github.com/terraform-providers/terraform-provider-oci/issues/600)
+- Specifying lifecycle state in container engine cluster datasource. Issue [#600](https://github.com/terraform-providers/terraform-provider-oci/issues/600)
+- Importing the assign_public_ip attribute for instances. Issue [#593](https://github.com/terraform-providers/terraform-provider-oci/issues/593)
 
 ## 3.1.1 (September 21, 2018)
 

oci/core_instance_resource.go

@@ -790,9 +790,8 @@ func CreateVnicDetailsToMap(obj *oci_core.Vnic, createVnicDetails map[string]int
 		assignPublicIP, _ := NormalizeBoolString(createVnicDetails["assign_public_ip"].(string)) // Must be valid.
 		result["assign_public_ip"] = assignPublicIP
 	} else {
-		// Set to "true" in case "create_vnic_details" is ommited altogether & the default value for
-		// "assign_public_ip" doesn't kick in.
-		result["assign_public_ip"] = "true"
+		// We may be importing this value; so let's set it to whether the public IP is set.
+		result["assign_public_ip"] = strconv.FormatBool(obj.PublicIp != nil && *obj.PublicIp != "")
 	}
 
 	if obj.DefinedTags != nil {

oci/core_instance_test.go

@@ -376,7 +376,6 @@ data "oci_core_instances" "test_instances" {
 				ImportState:       true,
 				ImportStateVerify: true,
 				ImportStateVerifyIgnore: []string{
-					"create_vnic_details",
 					// TODO: extended_metadata intentionally not set in resource Gets, even though supported
 					// by GetInstance calls. Remove this when the issue is resolved.
 					"extended_metadata",