Database.java

public @interface Database {
    public DatabaseType value();
}

DatabaseManager.java

public interface DatabaseManager {
    public void doStuff();
}

DatabaseType.java

public enum DatabaseType {
    SQLITE,
    MYSQL,
    ;
}

MysqlDatabaseManager.java

@Database(DatabaseType.MYSQL)
@PluginService
public class MysqlDatabaseManager implements DatabaseManager {
    public void doStuff() {
        System.out.println("Doing stuff in mysql");
    }
}

Plugin.java

public class Plugin extends JavaPlugin {
    public void onEnable() {
        BukkitGuice guice = new BukkitGuice(this);
        // In a real application you'd read the DatabaseType from the config and compare the value to that.
        guice.addConstraint(Database.class, database -> database.value() == DatabaseType.SQLITE);
        guice.start();
    }
}

SqliteDatabaseManager

@Database(DatabaseType.SQLITE)
@PluginService
public class SqliteDatabaseManager implements DatabaseManager {
    public void doStuff() {
        System.out.println("Doing stuff in sqlite");
    }
}