Correct way to setup plain java with maven?

I have this
```
"image": "mcr.microsoft.com/devcontainers/java:1-21-bullseye",
"features": {
"ghcr.io/devcontainers/features/java:1": {
"version": "none",
"installMaven": "true",
}
},
```
When running my maven command:
`mvn clean install`
I get the error message:
```
The JAVA_HOME environment variable is not defined correctly,
this environment variable is needed to run this program.

```
I would have expected that JAVA_HOME would be setup? I would also expect that the JDK or JRE installed would be the most upstream origin, eg OpenJDK.. It seems it an MS variant.