Texts in powerpoint thumbnail is not rendered correctly depending on Java version

Issue Summary

Texts in powerpoint thumbnail is not rendered correctly depending on Java version. Characters are overlaid each other.
As far as I confirmed,

• AdoptOpenJDK jdk8u202-b08 (which is a bundled one in most version of Confluence) can render correctly
• Oracle JRE jre-8u241-linux-x64 can render correctly
• AdoptOpenJDK jdk8u242-b08 is affected
• AdoptOpenJDK jdk-11.0.6+10 is affected
• AdoptOpenJDK jdk-11.0.5+10 is affected (it's bundled with 7.4.0)

Steps to Reproduce

1. Prepare Linux OS and install some fonts to enable server side rendering
   I've tested with Ubuntu

   sudo apt-get update
   sudo apt-get install -y fontconfig
   apt-get install -y fonts-dejavu
   

1. Install Confluence from tar.gz and configure it to use AdoptOpenJDK jdk8u242-b08
2. Open the editor, and drag and drop sample.pptx on your browser.

Expected Results

sample.pptx is rendered correctly.

Actual Results

The text is squashed.

Workaround

Use jdk8u202-b08 as Supported Platforms suggests.

Some AdoptOpenJDK versions have bugs that impact Confluence. We recommend version jdk8u202 (see CONFSERVER-58784).

Or, if you are already using Java 11, upgrade to version 11.0.7.

Note: Confluence LTS version 7.4.3 and later is bundled with AdoptOpenJDK version 11.0.7+10, which is unaffected by this bug. However, if Confluence is running using an older JDK version which is affected, the bug will still be experienced.