to build jar with mainClass successfully
 <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-jar-plugin</artifactId>
                <configuration>
                    <archive>
                        <manifest>
                            <mainClass>com.livehereandnow.sudoku.app.Main</mainClass>
                        </manifest>
                    </archive>
                </configuration>
            </plugin>
        </plugins>
    </build>

mark@nb:~/zzz/sudoku1$ java -jar target/sudoku1-1.0.jar  009036040008070310007000060000000050090642030070000000020000400081090600040580900 2 1 --- Sudoku 9x9 ---
 . . 9 . 3 6 . 4 .
 . . 8 . 7 . 3 1 .
 . . 7 . . . . 6 .
 . . . . . . . 5 .
 . 9 . 6 4 2 . 3 .
 . 7 . . . . . . .
 . 2 . . . . 4 . .
 . 8 1 . 9 . 6 . .
 . 4 . 5 8 . 9 . .
known cells count: 27

 --- Sudoku 9x9 ---
 2 1 9 8 3 6 5 4 7
 4 6 8 9 7 5 3 1 2
 3 5 7 4 2 1 8 6 9
 8 3 4 7 1 9 2 5 6
 1 9 5 6 4 2 7 3 8
 6 7 2 3 5 8 1 9 4
 9 2 3 1 6 7 4 8 5
 5 8 1 2 9 4 6 7 3
 7 4 6 5 8 3 9 2 1
known cells count: 81