maven "Failed to load Main-Class manifest attribute from"

<build>
? <plugins>
?? <plugin>
??????????????? <groupId>org.apache.maven.plugins</groupId>
??????????????? <artifactId>maven-jar-plugin</artifactId>
??????????????? <configuration>
??????????????????? <archive>
????????????????????????????????? <addMavenDescriptor>false</addMavenDescriptor>
??????????????????????? <manifest>
????????????????????????????????? <mainClass>com.mycompany.app.App</mainClass>
??????????????????????? </manifest>
??????????????????? </archive>

????????????? </configuration>

</plugin>
</plugins>
</build>