Fix/route53 resolver rule remove defaults

.changelog/41523.txt

@@ -0,0 +1,3 @@
+```release-note:bug-fix
+resource/aws_route53_resolver_rule: Remove hardcoded defaults for `port` and `protocol` in `target_ip` to allow the AWS API to apply conditional defaults
+```

internal/service/route53resolver/rule.go

@@ -103,13 +103,13 @@ func resourceRule() *schema.Resource {
 						names.AttrPort: {
 							Type:         schema.TypeInt,
 							Optional:     true,
-							Default:      53,
+							Computed:     true,
 							ValidateFunc: validation.IntBetween(1, 65535),
 						},
 						names.AttrProtocol: {
 							Type:             schema.TypeString,
 							Optional:         true,
-							Default:          awstypes.ProtocolDo53,
+							Computed:         true,
 							ValidateDiagFunc: enum.Validate[awstypes.Protocol](),
 						},
 					},
@@ -381,7 +381,7 @@ func expandRuleTargetIPs(vTargetIps *schema.Set) []awstypes.TargetAddress {
 		if vIpv6, ok := mTargetIp["ipv6"].(string); ok && vIpv6 != "" {
 			targetAddress.Ipv6 = aws.String(vIpv6)
 		}
-		if vPort, ok := mTargetIp[names.AttrPort].(int); ok {
+		if vPort, ok := mTargetIp[names.AttrPort].(int); ok && vPort != 0 {
 			targetAddress.Port = aws.Int32(int32(vPort))
 		}
 		if vProtocol, ok := mTargetIp[names.AttrProtocol].(string); ok && vProtocol != "" {

internal/service/route53resolver/rule_test.go

@@ -319,7 +319,7 @@ func TestAccRoute53ResolverRule_forwardMultiProtocol(t *testing.T) {
 		CheckDestroy:             testAccCheckRuleDestroy(ctx, t),
 		Steps: []resource.TestStep{
 			{
-				Config: testAccRuleConfig_forward(rName, domainName),
+				Config: testAccRuleConfig_forwardMultiProtocol(rName, domainName, "Do53"),
 				Check: resource.ComposeTestCheckFunc(
 					testAccCheckRuleExists(ctx, t, resourceName, &rule),
 					resource.TestCheckResourceAttr(resourceName, names.AttrDomainName, domainName),
@@ -375,6 +375,46 @@ func TestAccRoute53ResolverRule_forwardMultiProtocol(t *testing.T) {
 	})
 }
 
+func TestAccRoute53ResolverRule_forwardAPIDefaults(t *testing.T) {
+	ctx := acctest.Context(t)
+	var rule awstypes.ResolverRule
+	resourceName := "aws_route53_resolver_rule.test"
+	epResourceName := "aws_route53_resolver_endpoint.test.0"
+	domainName := acctest.RandomDomainName()
+	rName := acctest.RandomWithPrefix(t, acctest.ResourcePrefix)
+
+	acctest.ParallelTest(ctx, t, resource.TestCase{
+		PreCheck:                 func() { acctest.PreCheck(ctx, t); testAccPreCheck(ctx, t) },
+		ErrorCheck:               acctest.ErrorCheck(t, names.Route53ResolverServiceID),
+		ProtoV5ProviderFactories: acctest.ProtoV5ProviderFactories,
+		CheckDestroy:             testAccCheckRuleDestroy(ctx, t),
+		Steps: []resource.TestStep{
+			{
+				Config: testAccRuleConfig_forward(rName, domainName),
+				Check: resource.ComposeTestCheckFunc(
+					testAccCheckRuleExists(ctx, t, resourceName, &rule),
+					resource.TestCheckResourceAttr(resourceName, names.AttrDomainName, domainName),
+					resource.TestCheckResourceAttr(resourceName, names.AttrName, rName),
+					resource.TestCheckResourceAttr(resourceName, "rule_type", "FORWARD"),
+					resource.TestCheckResourceAttrPair(resourceName, "resolver_endpoint_id", epResourceName, names.AttrID),
+					resource.TestCheckResourceAttr(resourceName, "target_ip.#", "1"),
+					resource.TestCheckTypeSetElemNestedAttrs(resourceName, "target_ip.*", map[string]string{
+						"ip": "192.0.2.6",
+					}),
+					// Verify that port and protocol are set by the API (computed), not by provider defaults.
+					resource.TestCheckResourceAttrSet(resourceName, "target_ip.0.port"),
+					resource.TestCheckResourceAttrSet(resourceName, "target_ip.0.protocol"),
+				),
+			},
+			{
+				ResourceName:      resourceName,
+				ImportState:       true,
+				ImportStateVerify: true,
+			},
+		},
+	})
+}
+
 func TestAccRoute53ResolverRule_forward_ipv6(t *testing.T) {
 	ctx := acctest.Context(t)
 	var rule1, rule2, rule3 awstypes.ResolverRule