refactor: address S2365 collection-copying property getters

Resolves SonarQube S2365 x3.

CalculationFilterGroup (Snowflake + SqlServer): the `Filters` getter
ran .Where(...).ToList() on every access. Convert to a plain
auto-property holding the raw collection plus a `GetValidFilters()`
method that does the filtering. Update internal IsValid() and the two
QueryConfigExtensions callers to use the new method.

HierarchicalData.AllChildData: part of the IHierarchicalData interface
and JSON-serialized; the transformation IS the property's contract.
Suppress S2365 with justification rather than refactor -- same pattern
as S3875.

Behavior change: CalculationFilterGroup JSON output now serializes the
raw filter collection rather than the pre-filtered one. Round-trip is
preserved; callers needing the filtered view must call GetValidFilters().

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/Strata.SqlTools.Snowflake/ExpressionFactory/Query/CalculationFilterGroup.cs

@@ -4,33 +4,31 @@ namespace Strata.SqlTools.Snowflake.ExpressionFactory.Query;
 
 public class CalculationFilterGroup
 {
-    [JsonIgnore]
-    private IEnumerable<CalculationFilter> _filters;
-
     // Hereditary logical operation applied to all Filters
     public LogicalOperator LogicalOperator { get; set; }
 
-    public IEnumerable<CalculationFilter> Filters
+    public IEnumerable<CalculationFilter> Filters { get; set; }
-    {
-        get => _filters?.Where(x => x.IsValid()).ToList() ?? new List<CalculationFilter>();
-        set => _filters = value;
-    }
 
     public CalculationFilterGroup()
     {
         LogicalOperator = LogicalOperator.And;
-        _filters = new List<CalculationFilter>();
+        Filters = new List<CalculationFilter>();
     }
 
     [JsonConstructor]
     public CalculationFilterGroup(IEnumerable<CalculationFilter> filters, LogicalOperator logicalOperator)
     {
-        _filters = filters;
+        Filters = filters;
         LogicalOperator = logicalOperator;
     }
 
+    public IEnumerable<CalculationFilter> GetValidFilters()
+    {
+        return Filters?.Where(x => x.IsValid()).ToList() ?? new List<CalculationFilter>();
+    }
+
     public bool IsValid()
     {
-        return Filters != null && Filters.Any();
+        return GetValidFilters().Any();
     }
 }

src/Strata.SqlTools.Snowflake/ExpressionFactory/Query/QueryConfigExtensions.cs

@@ -11,7 +11,7 @@ public static class QueryConfigExtensions
     public static int[] GetAllColumnIds(this QueryConfig queryConfig)
     {
         return queryConfig.Values.SelectMany(value => value.CalculationDataColumnIds)
-            .Union(queryConfig.Values.SelectMany(x => x.FilterGroups.SelectMany(y => y.Filters.Select(f => f.DataColumnId))))
+            .Union(queryConfig.Values.SelectMany(x => x.FilterGroups.SelectMany(y => y.GetValidFilters().Select(f => f.DataColumnId))))
             .Union(queryConfig.Rows.Select(row => row.DataColumnId))
             .Union(queryConfig.FilterGroups.SelectMany(filterGroup => filterGroup.Filters.Select(filter => filter.DataColumnId)))
             .ToArray();

src/Strata.SqlTools.SqlBreakdown/Expressions/InputPropertyExpression.cs

@@ -1,6 +1,7 @@
 using Strata.SqlTools.SqlBreakdown.Interfaces.Core;
 
 using System.Collections;
+using System.Diagnostics.CodeAnalysis;
 using System.Globalization;
 using System.Text.Json;
 using System.Text.Json.Serialization;
@@ -373,6 +374,7 @@ public class HierarchicalData : IHierarchicalData
 
     public IFlatData Data { get; set; }
 
+    [SuppressMessage("Major Code Smell", "S2365:Properties should not make collection or array copies", Justification = "AllChildData is part of the IHierarchicalData interface contract and is JSON-serialized (see Data.json). The flatten-on-get / group-on-set transformation is the deliberate purpose of the property — _childDataMap is the storage form, the property is the wire form.")]
     public IEnumerable<IHierarchicalData> AllChildData
     {
         get => _childDataMap.SelectMany(x => x.Value).ToList();

src/Strata.SqlTools.SqlServer/ExpressionFactory/Query/CalculationFilterGroup.cs

@@ -4,33 +4,31 @@ namespace Strata.SqlTools.SqlServer.ExpressionFactory.Query;
 
 public class CalculationFilterGroup
 {
-    [JsonIgnore]
-    private IEnumerable<CalculationFilter> _filters;
-
     // Hereditary logical operation applied to all Filters
     public LogicalOperator LogicalOperator { get; set; }
 
-    public IEnumerable<CalculationFilter> Filters
+    public IEnumerable<CalculationFilter> Filters { get; set; }
-    {
-        get => _filters?.Where(x => x.IsValid()).ToList() ?? new List<CalculationFilter>();
-        set => _filters = value;
-    }
 
     public CalculationFilterGroup()
     {
         LogicalOperator = LogicalOperator.And;
-        _filters = new List<CalculationFilter>();
+        Filters = new List<CalculationFilter>();
     }
 
     [JsonConstructor]
     public CalculationFilterGroup(IEnumerable<CalculationFilter> filters, LogicalOperator logicalOperator)
     {
-        _filters = filters;
+        Filters = filters;
         LogicalOperator = logicalOperator;
     }
 
+    public IEnumerable<CalculationFilter> GetValidFilters()
+    {
+        return Filters?.Where(x => x.IsValid()).ToList() ?? new List<CalculationFilter>();
+    }
+
     public bool IsValid()
     {
-        return Filters != null && Filters.Any();
+        return GetValidFilters().Any();
     }
 }

src/Strata.SqlTools.SqlServer/ExpressionFactory/Query/QueryConfigExtensions.cs

@@ -11,7 +11,7 @@ public static class QueryConfigExtensions
     public static int[] GetAllColumnIds(this QueryConfig queryConfig)
     {
         return queryConfig.Values.SelectMany(value => value.CalculationDataColumnIds)
-            .Union(queryConfig.Values.SelectMany(x => x.FilterGroups.SelectMany(y => y.Filters.Select(f => f.DataColumnId))))
+            .Union(queryConfig.Values.SelectMany(x => x.FilterGroups.SelectMany(y => y.GetValidFilters().Select(f => f.DataColumnId))))
             .Union(queryConfig.Rows.Select(row => row.DataColumnId))
             .Union(queryConfig.FilterGroups.SelectMany(filterGroup => filterGroup.Filters.Select(filter => filter.DataColumnId)))
             .ToArray();