Let us assume you have several environments like dev-01, dev-02, test-01, test-02 and finally prod. Furthermore we make the whole situation more or less simple and we assume having only a single module build which produces a single war file as result.
To use the MultiEnv Maven Plugin you can simple create the following supplemental structure in your module apart of the war module configuration:
src
├── main
├── environments
├── dev-01
│ └── first.properties
├── dev-02
│ └── first.properties
├── test-01
│ └── first.properties
├── test-02
│ └── first.properties
└── prod
└── first.properties
In result the MultiEnv Maven Plugin will automatically create the appropriate war files containing the configuration file first.properties which might contain some information like the database connections url etc. for the appropriate environment.
The environment name (directory name) will automatically being used as classifier for the appropriate artifact. So we would get the following files after running MultiEnv Maven Plugin via (assuming you have configured it correctly):
mvn clean package
If you need to add a new environment this can simply achieved by adding the appropriate directory under environments which can be named for example qa-01 plus the configuration you would like to add there.
A new call to mvn clean package will identify the new environment (directory) and now produces a supplemental package for the qa-01 environment as well.
This would result into the following artifact list:
Those artifacts are ready to be deployed to the appropriate environment (Of course the application inside must handle the reading of the configuration files).