Documentation for app.config transforms fails for similarly named keys

[Axemasta]

Description

If you have 2 app config names that are similarly named (ie AppCenterAndroidSecret and AppCenterIosSecret) the config transforms will not be applied properly. The config transform is using Microsoft.Web.XmlTransform so that issue will be caused by that library, however the configuration of the XML can be updated in order to have both of these keys match.

Reproduction Steps

Steps to reproduce the behavior:

1. Open the AppConfigSample solution
2. Run the sample app (android or ios, i tested on ios but both platforms are affected)
3. Try and apply the "Debug" transform
4. The value for foo is not updated when xdt:Locator attribute is not present

Expected Behavior

The following replacements occur:	Key	Original	Replacement
foo	my foo	transformedFoo
foo2	my bar	transformedFoo2

Expected transformed XML document:

<?xml version="1.0" encoding="utf-8"?>
<configuration>
  <appSettings>
    <add key="foo" value="transformedFoo"/>
    <add key="foo2" value="transformedFoo2"/>
    <add key="Environment" value="Debug"/>
  </appSettings>
  <connectionStrings>
    <add name="test" providerName="my provider" connectionString="my connection string"/>
  </connectionStrings>
</configuration>

Actual Behavior

The value for foo is not replaced and instead is empty:	Key	Original	Replacement
foo	my foo
foo2	my bar	transformedFoo2

Here is the transformed xml as it gets returned by TransformHelper (sb.ToString())

<?xml version="1.0" encoding="utf-8"?>
<configuration>
  <appSettings>
    <add key="foo2" value="transformedFoo2"/>
    <add key="foo2" value="my bar"/>
    <add key="Environment" value="Debug"/>
  </appSettings>
  <connectionStrings>
    <add name="test" providerName="my provider" connectionString="my connection string"/>
  </connectionStrings>
</configuration>

Environment

• OS: [macOS Monterey]
• IDE: [VSMac 2019]
• BuildTools Version: [2.0.245]
• IDE Version: [8.10.25]
• Build Target Framework: [|Xamarin.iOS & Xamarin.Android]

Reproduction App

I have forked this repo and have a branch with a reproduction of the issue (app-config-repro)

Proposed Fix

Update the documentation & sample app to include the xdt:Locator attribute for the transform XML aswell as a note about this behaviour.

[Axemasta]

Closing after merge of #317

Remember if your config looks like this:

<configuration>
  <appSettings>
    <add key="foo" value="my foo" />
    <add key="foo2" value="my foo 2" />
  </appSettings>
</configuration>

You MUST use the xdt:Locator attribute otherwise your config will fail to load properly 😁

This is a valid replace transform

```xml ```

This is an invalid replace transform

```xml ```