Maven versions-maven-plugin NullPointerException when invoking with parent pom

Question

I have a project folder structure where we use a parent pom and each subfolder contains its own pom.xml. Like this:

Project (pom.xml)
|- Addon-1 (pom.xml)
|- Addon-2 (pom.xml)
|- Addon-2 (pom_hotfix.xml)

Addon-1 and Addon-2 pom.xml contains a parent:

  <parent>
    <groupId>com.abc</groupId>
    <artifactId>abc</artifactId>
    <version>1.0.4</version>
    <relativePath>../pom.xml</relativePath>
  </parent>

In addition, the Addon-2 folder contains a second pom file, which doesn't have a parent. This is mandatory since the Hotfix is not allowed to contain the whole parent.

My pom_hotfix.xml looks like:

<project>
  <modelVersion>4.0.0</modelVersion>
  <artifactId>hotfix</artifactId>
  <groupId>com.abc</groupId>
  <name>hotfix</name>
  <version>1.0.10</version>
  <packaging>jar</packaging>
  <build>
    <resources>
      <resource>
        <directory>src/main/overlay/</directory>
        <excludes>
          <exclude></exclude>
        </excludes>
      </resource>
    </resources>
  </build>
</project>

The issue is now with the org.codehaus.mojo:versions-maven-plugin set command. If I invoke as follows:

mvn -B org.codehaus.mojo:versions-maven-plugin:2.7:set -DnewVersion=2.0.2 -f pom_hotfix.xml -X

I always receive the following error.

 ✔  mvn -B org.codehaus.mojo:versions-maven-plugin:2.7:set -DnewVersion=2.0.2 -f pom_hotfix.xml
[INFO] Scanning for projects...
[INFO]
[INFO] ---------------< com.abc:hotfix >---------------
[INFO] Building hotfix 1.0.10
[INFO] --------------------------------[ jar ]---------------------------------
[INFO]
[INFO] --- versions-maven-plugin:2.7:set (default-cli) @ hotfix ---
[INFO] Searching for local aggregator root...
[INFO] Local aggregation root: /Users/abc/Project/
[INFO] Processing change of com.abc:hotfix:1.0.10 -> 2.0.2
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  1.264 s
[INFO] Finished at: 2020-07-13T11:27:41+02:00
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal org.codehaus.mojo:versions-maven-plugin:2.7:set (default-cli) on project fixpack: Execution default-cli of goal org.codehaus.mojo:versions-maven-plugin:2.7:set failed. NullPointerException -> [Help 1]
[ERROR]
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR]
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/PluginExecutionException

If I temporarily remove the parent pom.xml in the Project folder, it's working fine. My goal is tho bump version inside of pom_hotfix.xml. I have no idea why I receive a null pointer.