Port MetadataLoadContext.CoreAssembly nullability changes from dotnet/runtime#126142

xml/System.Reflection/MetadataLoadContext.xml

@@ -83,7 +83,7 @@ For more information and examples, see [How to: Inspect assembly contents using
       </Docs>
     </Member>
     <Member MemberName="CoreAssembly">
-      <MemberSignature Language="C#" Value="public System.Reflection.Assembly? CoreAssembly { get; }" />
+      <MemberSignature Language="C#" Value="public System.Reflection.Assembly CoreAssembly { get; }" />
       <MemberSignature Language="ILAsm" Value=".property instance class System.Reflection.Assembly CoreAssembly" />
       <MemberSignature Language="DocId" Value="P:System.Reflection.MetadataLoadContext.CoreAssembly" />
       <MemberSignature Language="VB.NET" Value="Public ReadOnly Property CoreAssembly As Assembly" />
@@ -94,12 +94,6 @@ For more information and examples, see [How to: Inspect assembly contents using
         <AssemblyName>System.Reflection.MetadataLoadContext</AssemblyName>
         <AssemblyVersion>11.0.0.0</AssemblyVersion>
       </AssemblyInfo>
-      <Attributes>
-        <Attribute FrameworkAlternate="net-10.0-pp;net-11.0-pp">
-          <AttributeName Language="C#">[System.Runtime.CompilerServices.Nullable(2)]</AttributeName>
-          <AttributeName Language="F#">[&lt;System.Runtime.CompilerServices.Nullable(2)&gt;]</AttributeName>
-        </Attribute>
-      </Attributes>
       <ReturnValue>
         <ReturnType>System.Reflection.Assembly</ReturnType>
       </ReturnValue>
@@ -113,46 +107,18 @@ For more information and examples, see [How to: Inspect assembly contents using
 
 The core assembly is treated differently than other assemblies because references to these well-known types do not include the assembly reference, unlike normal types.
 
-Typically, this assembly is named "mscorlib" or "netstandard". If the core assembly cannot be found, the value will be `null`, and many other reflection methods, including those that parse method signatures, will throw an exception.
+Typically, this assembly is named "System.Runtime", "mscorlib", or "netstandard".
 
-The `CoreAssembly` is determined by passing the `coreAssemblyName` parameter passed to the <xref:System.Reflection.MetadataAssemblyResolver> constructor
-to the <xref:System.Reflection.MetadataAssemblyResolver.Resolve*?displayProperty=nameWithType> method.
+The `CoreAssembly` is determined by passing the `coreAssemblyName` parameter to the <xref:System.Reflection.MetadataLoadContext> constructor,
+which in turn passes it to the <xref:System.Reflection.MetadataAssemblyResolver.Resolve*?displayProperty=nameWithType> method.
 
 If no `coreAssemblyName` argument was specified in the constructor of <xref:System.Reflection.MetadataLoadContext>, then default values are used, including "mscorlib", "System.Runtime" and "netstandard".
 
 The designated core assembly does not need to contain the core types directly. It can type forward them to other assemblies. Thus, it is perfectly permissible to use the mscorlib facade as the designated core assembly.
 
 Note that <xref:System.Runtime> is not an ideal core assembly because it excludes some of the interop-related pseudo-custom attribute types such as <xref:System.Runtime.InteropServices.DllImportAttribute>. However, it can serve if you have no interest in those attributes. The CustomAttributes API will skip those attributes if the core assembly does not include the necessary types.
 
-The core assembly is not loaded until necessary. The following APIs do not trigger the search for the core assembly:
-
-* <xref:System.Reflection.MetadataLoadContext.LoadFromStream*?displayProperty=nameWithType>
-* <xref:System.Reflection.MetadataLoadContext.LoadFromAssemblyPath*?displayProperty=nameWithType>
-* <xref:System.Reflection.MetadataLoadContext.LoadFromByteArray*?displayProperty=nameWithType>
-* <xref:System.Reflection.Assembly.GetName*?displayProperty=nameWithType>
-* <xref:System.Reflection.Assembly.FullName?displayProperty=nameWithType>
-* <xref:System.Reflection.Assembly.GetReferencedAssemblies*?displayProperty=nameWithType>
-* <xref:System.Reflection.Assembly.GetTypes*?displayProperty=nameWithType>
-* <xref:System.Reflection.Assembly.DefinedTypes?displayProperty=nameWithType>
-* <xref:System.Reflection.Assembly.GetExportedTypes*?displayProperty=nameWithType>
-* <xref:System.Reflection.Assembly.GetForwardedTypes*?displayProperty=nameWithType>
-* <xref:System.Reflection.Assembly.GetType(System.String,System.Boolean,System.Boolean)?displayProperty=nameWithType>
-* <xref:System.Type.Name?displayProperty=nameWithType>
-* <xref:System.Type.FullName?displayProperty=nameWithType>
-* <xref:System.Type.AssemblyQualifiedName?displayProperty=nameWithType>
-
-If a core assembly cannot be found or if the core assembly is missing types, this will affect the behavior of the <xref:System.Reflection.MetadataLoadContext> as follows:
-
-* APIs that need to parse signatures or typespecs and return the results as <xref:System.Type> objects will throw an exception. For example:
-
-  * <xref:System.Reflection.MethodInfo.ReturnType?displayProperty=nameWithType>
-  * <xref:System.Reflection.MethodBase.GetParameters*?displayProperty=nameWithType>
-  * <xref:System.Type.BaseType?displayProperty=nameWithType>
-  * <xref:System.Type.GetInterfaces*?displayProperty=nameWithType>
-
-* APIs that need to compare types to well-known core types will not throw an exception, and the comparison will evaluate to `false`. For example, if you do not specify a core assembly, <xref:System.Type.IsPrimitive> will return `false` for everything, even types named <xref:System.Int32>. Similarly, <xref:System.Type.GetTypeCode*?displayProperty=nameWithType> will return <xref:System.TypeCode.Object> for everything.
-
-* If a metadata entity sets flags that surface as a pseudo-custom attribute, and the core assembly does not contain the pseudo-custom attribute type, the necessary constructor or any of the parameter types of the constructor, the <xref:System.Reflection.MetadataLoadContext> will not throw. It will omit the pseudo-custom attribute from the list of returned attributes.
+If a core assembly cannot be found, the constructor of <xref:System.Reflection.MetadataLoadContext> will throw an exception.
           ]]></format>
         </remarks>
       </Docs>