Merge pull request #4048 from dotnet/stephentoub-patch-1

Remove incorrect nullable information from GetIPv4Properties

Author: davidsh

xml/System.Net.NetworkInformation/IPInterfaceProperties.xml

@@ -387,13 +387,11 @@
       <Parameters />
       <Docs>
         <summary>Provides Internet Protocol version 4 (IPv4) configuration data for this network interface.</summary>
-        <returns>An <see cref="T:System.Net.NetworkInformation.IPv4InterfaceProperties" /> object that contains IPv4 configuration data, or <see langword="null" /> if no data is available for the interface.</returns>
+        <returns>An <see cref="T:System.Net.NetworkInformation.IPv4InterfaceProperties" /> object that contains IPv4 configuration data.</returns>
         <remarks>
           <format type="text/markdown"><![CDATA[  
   
 ## Remarks  
- This property returns `null` for <xref:System.Net.NetworkInformation.NetworkInterfaceType.Loopback> interfaces.  
-  
  For a detailed description of the information available for an interface that supports IPv4, see the <xref:System.Net.NetworkInformation.IPv4InterfaceProperties> class documentation. Note that the object returned by the <xref:System.Net.NetworkInformation.IPInterfaceProperties.GetIPv4Properties%2A> method reflects the configuration as of the time the object is created. This information is not updated dynamically.  
   
  ]]></format>