Extension Manager raises a conflict on WebPreferences on upgrade while pages are nearly strictly identical

Steps to reproduce

• Unzip into a local Maven repository the enclosed Maven repository maven-repository-application-test.zip containing a test extension named "application-test-ui" in versions 1.0 and 1.1.
• Enable extension conflict setup in your profile
• Install org.xwiki.contrib:application-test-ui in version 1.0
• Upgrade it to version 1.1

Actual result

For page Test.WebPreferences, EM prompts a merge conflict while 1) the XML of the two pages in the two versions are strictly identical, 2) a comparison of the exported version of the installed Test.WebPreferences with the one in the extension source code shows no difference on the XClass and shows empty object fields added in the exported version, such as the ones below and a few others:

    <property>
      <admin_email/>
    </property>
    <property>
      <comment_anonymous/>
    </property>
    <property>
      <comment_registered/>
    </property>
    <property>
      <confirmation_email_content/>
    </property>

NB: both the initial export and the export after installation were performed on the same XS version: 14.4.5.

Expected result

The new version of Test.WebPreferences is installed without EM raising a conflict and/or the initial export of Test.WebPreferences contains the empty fields added on installation.