A multi-module parent POM declares the following BOM import:
io.s
My answer would be really similar to @Didier L. I was getting error due to the .xml file extension mvn org.apache.maven.plugins:maven-help-plugin:3.2.0:effective-pom -Dverbose=true -Doutput=effective-pom
mvn org.apache.maven.plugins:maven-help-plugin:3.2.0:effective-pom -Dverbose=true -Doutput=effective-pom