Maven no main manifest attribute when generate jar for project

pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>

  <groupId>zhou</groupId>
  <artifactId>execrise</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <packaging>jar</packaging>

  <name>execrise</name>
  <url>http://maven.apache.org</url>

  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
  </properties>

  <dependencies>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>3.8.1</version>
      <scope>test</scope>
    </dependency>
<dependency> <groupId>com.google.guava</groupId>
    <artifactId>guava</artifactId>
    <version>19.0</version>
</dependency>
  </dependencies>
  <!-- https://mvnrepository.com/artifact/com.google.guava/guava -->
  
  <build>
  <plugins>
    <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-shade-plugin</artifactId>
        <version>1.2.1</version>
        <executions>
            <execution>
                <phase>package</phase>
                <goals>
                        <goal>shade</goal>
                </goals>
                    <configuration>
                        <transformers>
                            <transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
                                <mainClass>zhou.execrise.App</mainClass>
                            </transformer>
                        </transformers>
                    </configuration>
            </execution>
        </executions>
     </plugin>
  </plugins>
</build>
 </project>

attention

plugin

        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-shade-plugin</artifactId>
        <version>1.2.1</version>

package route

 <mainClass>zhou.execrise.App</mainClass>