Added expandIconColor property on ExpansionPanelList Widget (#115950)

* Create expanIconColor doc template

* Add expandIconColor property to ExpansionPanelList

* Added tests for expandIconColor on ExpansionPanelList & radio

* Removed trailing spaces

packages/flutter/lib/src/material/expand_icon.dart

@@ -66,7 +66,7 @@ class ExpandIcon extends StatefulWidget {
   /// This property must not be null. It defaults to 8.0 padding on all sides.
   final EdgeInsetsGeometry padding;
 
-
+  /// {@template flutter.material.ExpandIcon.color}
   /// The color of the icon.
   ///
   /// Defaults to [Colors.black54] when the theme's
@@ -74,6 +74,7 @@ class ExpandIcon extends StatefulWidget {
   /// [Colors.white60] when it is [Brightness.dark]. This adheres to the
   /// Material Design specifications for [icons](https://material.io/design/iconography/system-icons.html#color)
   /// and for [dark theme](https://material.io/design/color/dark-theme.html#ui-application)
+  /// {@endtemplate}
   final Color? color;
 
   /// The color of the icon when it is disabled,

packages/flutter/lib/src/material/expansion_panel.dart

@@ -168,6 +168,7 @@ class ExpansionPanelList extends StatefulWidget {
     this.expandedHeaderPadding = _kPanelHeaderExpandedDefaultPadding,
     this.dividerColor,
     this.elevation = 2,
+    this.expandIconColor,
   }) : assert(children != null),
        assert(animationDuration != null),
        _allowOnlyOnePanelOpen = false,
@@ -195,6 +196,7 @@ class ExpansionPanelList extends StatefulWidget {
     this.expandedHeaderPadding = _kPanelHeaderExpandedDefaultPadding,
     this.dividerColor,
     this.elevation = 2,
+    this.expandIconColor,
   }) : assert(children != null),
        assert(animationDuration != null),
        _allowOnlyOnePanelOpen = true;
@@ -249,6 +251,9 @@ class ExpansionPanelList extends StatefulWidget {
   /// By default, the value of elevation is 2.
   final double elevation;
 
+  /// {@macro flutter.material.ExpandIcon.color}
+  final Color? expandIconColor;
+
   @override
   State<StatefulWidget> createState() => _ExpansionPanelListState();
 }
@@ -356,6 +361,7 @@ class _ExpansionPanelListState extends State<ExpansionPanelList> {
       Widget expandIconContainer = Container(
         margin: const EdgeInsetsDirectional.only(end: 8.0),
         child: ExpandIcon(
+          color: widget.expandIconColor,
           isExpanded: _isChildExpanded(index),
           padding: const EdgeInsets.all(16.0),
           onPressed: !child.canTapOnHeader

packages/flutter/test/material/expansion_panel_test.dart

@@ -1390,6 +1390,55 @@ void main() {
     expect(boxDecoration.border!.top.color, dividerColor);
   });
 
+  testWidgets('ExpansionPanelList respects expandIconColor', (WidgetTester tester) async {
+    const Color expandIconColor = Colors.blue;
+    await tester.pumpWidget(MaterialApp(
+      home: SingleChildScrollView(
+        child: ExpansionPanelList(
+          expandIconColor: expandIconColor,
+          children: <ExpansionPanel>[
+            ExpansionPanel(
+              canTapOnHeader: true,
+              body: const SizedBox.shrink(),
+              headerBuilder: (BuildContext context, bool isExpanded) {
+                return const SizedBox.shrink();
+              }
+            )
+          ],
+        ),
+      ),
+    ));
+
+    final ExpandIcon expandIcon = tester.widget(find.byType(ExpandIcon));
+
+    expect(expandIcon.color, expandIconColor);
+  });
+
+  testWidgets('ExpansionPanelList.radio respects expandIconColor', (WidgetTester tester) async {
+    const Color expandIconColor = Colors.blue;
+    await tester.pumpWidget(MaterialApp(
+      home: SingleChildScrollView(
+        child: ExpansionPanelList.radio(
+          expandIconColor: expandIconColor,
+          children: <ExpansionPanelRadio>[
+            ExpansionPanelRadio(
+              canTapOnHeader: true,
+              body: const SizedBox.shrink(),
+              headerBuilder: (BuildContext context, bool isExpanded) {
+                return const SizedBox.shrink();
+              },
+              value: true
+            )
+          ],
+        ),
+      ),
+    ));
+
+    final ExpandIcon expandIcon = tester.widget(find.byType(ExpandIcon));
+
+    expect(expandIcon.color, expandIconColor);
+  });
+
   testWidgets('elevation is propagated properly to MergeableMaterial', (WidgetTester tester) async {
     const double elevation = 8;