Extract duplicated list type handling logic into reusable helper (#1559)

* Initial plan

* Refactor: extract duplicated list type handling into reusable helper function

- Created EnsureTypedList helper in typeutils package
- Replaced three instances of duplicated logic for handling untyped zero-value lists
- Removed unused strings import from resource.go
- All three instances (CategorizationFilters, Influencers, CustomRules) now use the centralized helper

Co-authored-by: neiljbrookes <[email protected]>

---------

Co-authored-by: copilot-swe-agent[bot] <[email protected]>
Co-authored-by: neiljbrookes <[email protected]>

Author: Copilot

internal/elasticsearch/ml/anomaly_detection_job/models_tf.go

@@ -362,23 +362,15 @@ func (tfModel *AnomalyDetectionJobTFModel) convertAnalysisConfigFromAPI(ctx cont
 	var categorizationFiltersDiags diag.Diagnostics
 	analysisConfigTF.CategorizationFilters, categorizationFiltersDiags = typeutils.NonEmptyListOrDefault(ctx, analysisConfigTF.CategorizationFilters, types.StringType, apiConfig.CategorizationFilters)
 	diags.Append(categorizationFiltersDiags...)
-	// If the existing value was an untyped zero-value list (common during import), force a typed null list.
-	if analysisConfigTF.CategorizationFilters.ElementType(ctx) == nil {
-		analysisConfigTF.CategorizationFilters = types.ListNull(types.StringType)
-	} else if _, ok := analysisConfigTF.CategorizationFilters.ElementType(ctx).(basetypes.DynamicType); ok {
-		analysisConfigTF.CategorizationFilters = types.ListNull(types.StringType)
-	}
+	// Ensure the list is properly typed (handles untyped zero-value lists from import)
+	analysisConfigTF.CategorizationFilters = typeutils.EnsureTypedList(ctx, analysisConfigTF.CategorizationFilters, types.StringType)
 
 	// Convert influencers
 	var influencersDiags diag.Diagnostics
 	analysisConfigTF.Influencers, influencersDiags = typeutils.NonEmptyListOrDefault(ctx, analysisConfigTF.Influencers, types.StringType, apiConfig.Influencers)
 	diags.Append(influencersDiags...)
-	// If the existing value was an untyped zero-value list (common during import), force a typed null list.
-	if analysisConfigTF.Influencers.ElementType(ctx) == nil {
-		analysisConfigTF.Influencers = types.ListNull(types.StringType)
-	} else if _, ok := analysisConfigTF.Influencers.ElementType(ctx).(basetypes.DynamicType); ok {
-		analysisConfigTF.Influencers = types.ListNull(types.StringType)
-	}
+	// Ensure the list is properly typed (handles untyped zero-value lists from import)
+	analysisConfigTF.Influencers = typeutils.EnsureTypedList(ctx, analysisConfigTF.Influencers, types.StringType)
 
 	// Convert detectors
 	if len(apiConfig.Detectors) > 0 {
@@ -449,12 +441,8 @@ func (tfModel *AnomalyDetectionJobTFModel) convertAnalysisConfigFromAPI(ctx cont
 			var customRulesDiags diag.Diagnostics
 			detectorsTF[i].CustomRules, customRulesDiags = typeutils.NonEmptyListOrDefault(ctx, originalDetector.CustomRules, types.ObjectType{AttrTypes: getCustomRuleAttrTypes()}, apiConfig.Detectors[i].CustomRules)
 			diags.Append(customRulesDiags...)
-			// If the existing value was an untyped zero-value list (common during import), force a typed null list.
-			if detectorsTF[i].CustomRules.ElementType(ctx) == nil {
-				detectorsTF[i].CustomRules = types.ListNull(types.ObjectType{AttrTypes: getCustomRuleAttrTypes()})
-			} else if _, ok := detectorsTF[i].CustomRules.ElementType(ctx).(basetypes.DynamicType); ok {
-				detectorsTF[i].CustomRules = types.ListNull(types.ObjectType{AttrTypes: getCustomRuleAttrTypes()})
-			}
+			// Ensure the list is properly typed (handles untyped zero-value lists from import)
+			detectorsTF[i].CustomRules = typeutils.EnsureTypedList(ctx, detectorsTF[i].CustomRules, types.ObjectType{AttrTypes: getCustomRuleAttrTypes()})
 		}
 		analysisConfigTF.Detectors = detectorsTF
 	}

internal/utils/typeutils/list.go

@@ -6,6 +6,7 @@ import (
 	"github.com/hashicorp/terraform-plugin-framework/attr"
 	"github.com/hashicorp/terraform-plugin-framework/diag"
 	"github.com/hashicorp/terraform-plugin-framework/types"
+	"github.com/hashicorp/terraform-plugin-framework/types/basetypes"
 )
 
 func NonEmptyListOrDefault[T any](ctx context.Context, original types.List, elemType attr.Type, slice []T) (types.List, diag.Diagnostics) {
@@ -15,3 +16,22 @@ func NonEmptyListOrDefault[T any](ctx context.Context, original types.List, elem
 
 	return types.ListValueFrom(ctx, elemType, slice)
 }
+
+// EnsureTypedList converts untyped zero-value lists to properly typed null lists.
+// This is commonly needed during import operations where the framework may create
+// untyped lists with DynamicPseudoType elements, which causes type conversion errors.
+// If the list already has a proper type, it is returned unchanged.
+func EnsureTypedList(ctx context.Context, list types.List, elemType attr.Type) types.List {
+	// Check if the list has no element type (nil)
+	if list.ElementType(ctx) == nil {
+		return types.ListNull(elemType)
+	}
+
+	// Check if the list has a dynamic pseudo type
+	if _, ok := list.ElementType(ctx).(basetypes.DynamicType); ok {
+		return types.ListNull(elemType)
+	}
+
+	// List is already properly typed, return as-is
+	return list
+}