Example docs on using custom keystores

## I expect

Examples using custom keystores for java

## Note

```docker-compose.yaml
volumes:
- /home/user/.m2:/code/.m2
environments:
- MAVEN_OPTS= -Djavax.net.ssl.trustStore=/code/cacerts -Djavax.net.ssl.trustStorePassword=changeit
- MAVEN_ARGS=-s settings.xml
```