elbv2/listener,target_group: Fix import differences, zero-values for absent values

.changelog/39413.txt

@@ -0,0 +1,31 @@
+```release-note:bug
+resource/aws_lb_listener_rule: Fix several of the arguments to avoiding setting zero-values in situations where they shouldn't causing warnings and import differences
+```
+
+```release-note:bug
+resource/aws_lb_target_group: Fix several of the arguments to avoiding setting zero-values in situations where they shouldn't causing warnings and import differences
+```
+
+```release-note:bug
+resource/aws_lb_listener: Fix several of the arguments to avoiding setting zero-values in situations where they shouldn't causing warnings and import differences
+```
+
+```release-note:bug
+resource/aws_lb_listener: Remove the limitation preventing setting both default_action.0.target_group_arn and default_action.0.forward to align with the AWS API which allows you to specify both a target group list and a top-level target group ARN if the ARNs match
+```
+
+```release-note:note
+resource/aws_lb_listener: When importing a listener that has either a default action top-level target group ARN or a default action defining a forward action defining a target group with an ARN, include both in the configuration to avoid import differences
+```
+
+```release-note:bug
+resource/aws_alb_listener: Fix several of the arguments to avoiding setting zero-values in situations where they shouldn't causing warnings and import differences
+```
+
+```release-note:bug
+resource/aws_alb_listener: Remove the limitation preventing setting both default_action.0.target_group_arn and default_action.0.forward to align with the AWS API which allows you to specify both a target group list and a top-level target group ARN if the ARNs match
+```
+
+```release-note:note
+resource/aws_alb_listener: When importing a listener that has either a default action top-level target group ARN or a default action defining a forward action defining a target group with an ARN, include both in the configuration to avoid import differences
+```

internal/acctest/import.go

@@ -0,0 +1,61 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
+package acctest
+
+import (
+	"errors"
+	"fmt"
+
+	"github.com/hashicorp/terraform-plugin-testing/helper/resource"
+	"github.com/hashicorp/terraform-plugin-testing/terraform"
+)
+
+// ComposeAggregateImportStateCheckFunc lets you compose multiple ImportStateCheckFunc into
+// a single ImportStateCheckFunc.
+func ComposeAggregateImportStateCheckFunc(fs ...resource.ImportStateCheckFunc) resource.ImportStateCheckFunc {
+	return func(is []*terraform.InstanceState) error {
+		var result []error
+
+		for i, f := range fs {
+			if err := f(is); err != nil {
+				result = append(result, fmt.Errorf("Import check %d/%d error: %w", i+1, len(fs), err))
+			}
+		}
+
+		return errors.Join(result...)
+	}
+}
+
+func ImportCheckResourceAttr(key, expected string) resource.ImportStateCheckFunc {
+	return func(is []*terraform.InstanceState) error {
+		if len(is) != 1 {
+			return fmt.Errorf("Attribute '%s' expected 1 instance state, got %d", key, len(is))
+		}
+
+		rs := is[0]
+		if rs.Attributes[key] != expected {
+			return fmt.Errorf("Attribute '%s' expected %s, got %s", key, expected, rs.Attributes[key])
+		}
+		return nil
+	}
+}
+
+func ImportCheckResourceAttrSet(key string, set bool) resource.ImportStateCheckFunc {
+	return func(is []*terraform.InstanceState) error {
+		if len(is) != 1 {
+			return fmt.Errorf("Attribute '%s' expected 1 instance state, got %d", key, len(is))
+		}
+
+		rs := is[0]
+		if set && rs.Attributes[key] == "" {
+			return fmt.Errorf("Attribute '%s' expected to be set, got not set", key)
+		}
+
+		if !set && rs.Attributes[key] != "" {
+			return fmt.Errorf("Attribute '%s' expected to be not set, got set (%s)", key, rs.Attributes[key])
+		}
+
+		return nil
+	}
+}