Enable to exec:java runnables and not only mains with loosely coupled injections

[rmannibucau]

Goal is to enable to quickly use exec:java as an in place mojo replacement without having to bring all maven stack for simple needs.

Sample:

import java.util.Properties;
import java.util.function.BiConsumer;
import java.util.function.Function;

public final class ComputeLatest implements Runnable {
    private final Function<String, String> versionResolver;
    private final Properties properties;
    private final BiConsumer<String, String> updater;

    public ComputeLatest(final Function<String, String> highestVersionResolver,
                         final Properties systemProperties,
                         final BiConsumer<String, String> systemPropertiesUpdater) {
        this.versionResolver = highestVersionResolver;
        this.properties = systemProperties;
        this.updater = systemPropertiesUpdater;
    }

    public void run() {
        final var project = properties.getProperty("env.DEPLOY_PROJECT");
        final String ga = switch (project) {
            case "foo" -> "com.demo.app1:deploy";
            case "bar" -> "com.demo.app2:deploy";
            default -> "";
        };
        if (ga.isBlank()) { // ignore
            return;
        }

        var lastVersion = versionResolver.apply(ga);
        if (!lastVersion.endsWith("-SNAPSHOT")) { // likely local since m2 repo shouldn't get published snapshots
            final var lastDot = lastVersion.lastIndexOf('.') + 1;
            lastVersion = lastVersion.substring(0, lastDot) + (Integer.parseInt(lastVersion.substring(lastDot)) + 1) + "-snapshot";
        }
        updater.accept(ga.replace('.', '_').replace(':', '_') + ".latest", lastVersion);
    }
}

then use com_demo_app1_deploy.latest in any placeholder friendly downstream plugin.

[slawekjaranowski]

I would also consider to add example page with it in documentation

[rmannibucau]

adressed comments @slawekjaranowski if you want to have another look, thanks a lot to have spotted some issues, totally missed them yesterday.

[slawekjaranowski]

please fix copy paste in documentation