The <systemProperties> configuration property is deprecated and replaced by <systemPropertyVariables> instead. Surefire plugin is currently complaining with the following warning during the build:

[WARNING] Parameter 'systemProperties' is deprecated: Use systemPropertyVariables instead.

Also, using the systemPropertyVariables form allows project to easily add new values or override those inherited from the parent pom. For example, one could easily write the following to override the java.awt.headless property and add an extra one without loosing the defaults inherited from the parent pom:

<plugin>
  <groupId>org.apache.maven.plugins</groupId>
  <artifactId>maven-surefire-plugin</artifactId>
  <configuration>
    <systemPropertyVariables>
      <!-- Override what is inherited from parent -->
      <java.awt.headless>false</java.awt.headless>

      <!-- Additional property -->
      <foo>bar</foo>
    </systemPropertyVariables>
  </configuration>
</plugin> 

More information: https://maven.apache.org/surefire/maven-surefire-plugin/examples/system-properties.html