Redirect pages break when impersonating a user

• Type: Bug
• Status: Closed
• Resolution: Fixed
• Affects Version/s: 7.2.X
• Fix Version/s: 7.2.X
• Component/s: Core Infrastructure, Friendly URL Service
• Labels:
  • ee-ts
  • liferay-fixpack-dxp-9-7210
• Branch Version/s:
  7.2.x
• Backported to Branch:
  Committed
• Fix Priority: 3
• Git Pull Request: https://github.com/liferay/liferay-portal-ee/pull/21413

Reproduction Steps:

1. Set up a vanilla 7.2.x with the latest fix pack and add the following property to your portal-ext.properties file: "layout.first.pageable[url]=true (this allows the first page of a site to be of type "Link to URL).
2. Go to Control Panel --> Sites --> Sites and create a blank site "Test Site".
3. Add a private page to Test Site by going to Site Builder --> Pages --> Add a private page "Page" with the type "Link to Page" then add the following URL: http://localhost:8080/web/guest (this is the default page of the default site).
4. Create a user by going to Control Panel --> Users --> Users and Organizations and add a User then add this user to the created Site by going to "Memberships" and select the Test Site.
5. Go to Users --> Users and Organizations and find the created User and click on the 3 dot menu beside it and select "Impersonate User"
Note: The "doAsUserId" is appended to the URL. Using the profile drop-down in the top right, select "My Sites" and select the "Test Site"

Expected Result: The user is redirected to "/web/guest" with the "doAsUserId" request parameter intact.

Actual Result: the "doAsUserId" is request parameter value is broken, as the parameter and value have been appended to the URL a second time without a separating "&".

 http://localhost:8080/web/guest?doAsUserId=Lknmv1jIOcTDqEG8hcOgCQ%3D%3DdoAsUserId=Lknmv1jIOcTDqEG8hcOgCQ%3D%3D

 7.2.x @ ab8033b0691099263ee598d6d399472cf01e85c5