A prefix is a named alias for a plugin.
The prefix assignation is done automatically if the plugin naming convention is used:
Example of prefix configuration in the pom.xml
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-plugin-plugin</artifactId>
<version>3.4</version>
<configuration>
<goalPrefix>hello</goalPrefix>
</configuration>
........
</plugin>
<code dos>
mvn prefix:goal@executionId