Fix options Validation with objects have indexers (#92311)

Co-authored-by: Tarek Mahmoud Sayed <tarekms@microsoft.com>
Co-authored-by: Carlos Sánchez López <1175054+carlossanlop@users.noreply.github.com>

src/libraries/Microsoft.Extensions.Options.DataAnnotations/src/DataAnnotationValidateOptions.cs

@@ -95,7 +95,8 @@ private static bool TryValidateOptions(object options, string qualifiedName, Lis
 
             foreach (PropertyInfo propertyInfo in options.GetType().GetProperties(BindingFlags.Instance | BindingFlags.Public))
             {
-                if (propertyInfo.GetMethod is null)
+                // Indexers are properties which take parameters. Ignore them.
+                if (propertyInfo.GetMethod is null || propertyInfo.GetMethod.GetParameters().Length > 0)
                 {
                     continue;
                 }

src/libraries/Microsoft.Extensions.Options/tests/SourceGeneration.Unit.Tests/OptionsRuntimeTests.cs

@@ -177,6 +177,30 @@ public void TestValidationWithEnumeration()
                         result2.Failures);
         }
 
+        [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsNotBrowser))]
+        public void TestObjectsWithIndexerProperties()
+        {
+            DataAnnotationValidateOptions<MyDictionaryOptions> dataAnnotationValidateOptions1 = new("MyDictionaryOptions");
+            MyDictionaryOptionsOptionsValidator sourceGenOptionsValidator1 = new();
+
+            var options1 = new MyDictionaryOptions();
+            ValidateOptionsResult result1 = sourceGenOptionsValidator1.Validate("MyDictionaryOptions", options1);
+            ValidateOptionsResult result2 = dataAnnotationValidateOptions1.Validate("MyDictionaryOptions", options1);
+
+            Assert.True(result1.Succeeded);
+            Assert.True(result2.Succeeded);
+
+            DataAnnotationValidateOptions<MyListOptions<string>> dataAnnotationValidateOptions2 = new("MyListOptions");
+            MyListOptionsOptionsValidator sourceGenOptionsValidator2 = new();
+
+            var options2 = new MyListOptions<string>() { Prop = "test" };
+            result1 = sourceGenOptionsValidator2.Validate("MyListOptions", options2);
+            result2 = dataAnnotationValidateOptions2.Validate("MyListOptions", options2);
+
+            Assert.True(result1.Succeeded);
+            Assert.True(result2.Succeeded);
+        }
+
         [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsNotBrowser))]
         public void TestValidationWithCyclicReferences()
         {
@@ -302,6 +326,12 @@ public partial class MySourceGenOptionsValidator : IValidateOptions<MyOptions>
     {
     }
 
+    public class MyDictionaryOptions : Dictionary<string, string> { [Required] public string Prop { get; set; } = "test"; }
+    [OptionsValidator] public partial class MyDictionaryOptionsOptionsValidator : IValidateOptions<MyDictionaryOptions> { }
+
+    public class MyListOptions<T> : List<T> { [Required] public T Prop { get; set; } = default; }
+    [OptionsValidator] public partial class MyListOptionsOptionsValidator : IValidateOptions<MyListOptions<string>> { }
+
 #if NET8_0_OR_GREATER
     public class OptionsUsingNewAttributes
     {