Add support for repeated XML elements without a name attribute

src/libraries/Microsoft.Extensions.Configuration.Xml/src/XmlConfigurationElement.cs

@@ -0,0 +1,55 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System;
+using System.Collections.Generic;
+
+namespace Microsoft.Extensions.Configuration.Xml
+{
+    internal class XmlConfigurationElement
+    {
+        public string ElementName { get; }
+
+        public string Name { get; }
+
+        public string LineInfo { get; }
+
+        /// <summary>
+        /// The children of this element
+        /// </summary>
+        public List<XmlConfigurationElement>? Children { get; set; }
+
+        /// <summary>
+        /// The siblings of this element, including itself
+        /// Elements are considered siblings if they share the same element name and name attribute
+        /// This list is shared by each sibling
+        /// </summary>
+        public List<XmlConfigurationElement>? Siblings { get; set; }
+
+        public XmlConfigurationElementTextContent? TextContent { get; set; }
+
+        public List<XmlConfigurationElementAttributeValue>? Attributes { get; set; }
+
+        public XmlConfigurationElement(string elementName, string name, string lineInfo)
+        {
+            ElementName = elementName ?? throw new ArgumentNullException(nameof(elementName));
+            Name = name;
+            LineInfo = lineInfo;
+            Children = null;
+            Siblings = null;
+            TextContent = null;
+            Attributes = null;
+        }
+
+        public bool IsSiblingOf(XmlConfigurationElement xmlConfigurationElement)
+        {
+            if (xmlConfigurationElement is null)
+            {
+                throw new ArgumentNullException(nameof(xmlConfigurationElement));
+            }
+
+            return string.Equals(ElementName, xmlConfigurationElement.ElementName)
+                && string.Equals(Name, xmlConfigurationElement.Name);
+        }
+    }
+}

src/libraries/Microsoft.Extensions.Configuration.Xml/src/XmlConfigurationElementAttributeValue.cs

@@ -0,0 +1,23 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System;
+
+namespace Microsoft.Extensions.Configuration.Xml
+{
+    internal class XmlConfigurationElementAttributeValue
+    {
+        public XmlConfigurationElementAttributeValue(string attribute, string value, string lineInfo)
+        {
+            Attribute = attribute ?? throw new ArgumentNullException(nameof(attribute));
+            Value = value ?? throw new ArgumentNullException(nameof(value));
+            LineInfo = lineInfo;
+        }
+
+        public string Attribute { get; }
+
+        public string Value { get; }
+
+        public string LineInfo { get; }
+    }
+}

src/libraries/Microsoft.Extensions.Configuration.Xml/src/XmlConfigurationElementTextContent.cs

@@ -0,0 +1,20 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System;
+
+namespace Microsoft.Extensions.Configuration.Xml
+{
+    internal class XmlConfigurationElementTextContent
+    {
+        public XmlConfigurationElementTextContent(string textContent, string lineInfo)
+        {
+            TextContent = textContent ?? throw new ArgumentNullException(nameof(textContent));
+            LineInfo = lineInfo ?? throw new ArgumentNullException(nameof(lineInfo));
+        }
+
+        public string TextContent { get; }
+
+        public string LineInfo { get; }
+    }
+}