Deploying to Google app Engine - AppEngineException: Non zero exit: 2 - google-app-engine

Question

I am trying to deploy my Spring Boot application to Google App Engine but can't seem to figure out this exception.
[ERROR] Failed to execute goal com.google.cloud.tools:appengine-maven-plugin:2.2.0:deploy (default-cli) on project HowlingWolfe: App Engine application deployment failed: com.google.cloud.tools.appengine.operations.cloudsdk.process.ProcessHandlerException: com.google.cloud.tools.appengine.AppEngineException: Non zero exit: 2 -> [Help 1]
Here is my pom.xml:
<?xml version="1.0" encoding="UTF-8"?>
<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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.4.4</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>com.HowlingWolfe</groupId>
<artifactId>HowlingWolfe</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>HowlingWolfe</name>
<description>Howling Wolfe Canoe and Kayak Rentals</description>
<properties>
<java.version>1.8</java.version>
<maven.compiler.source>1.8</maven.compiler.source>
<maven.compiler.target>1.8</maven.compiler.target>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
<dependency>
<groupId>org.postgresql</groupId>
<artifactId>postgresql</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>com.google.code.gson</groupId>
<artifactId>gson</artifactId>
<version>2.8.6</version>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<optional>true</optional>
</dependency>
<dependency>
<groupId>com.sun.mail</groupId>
<artifactId>javax.mail</artifactId>
<version>1.6.2</version>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-security</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-autoconfigure</artifactId>
<version>2.4.2</version>
</dependency>
</dependencies>
<build>
<finalName>${artifactId}</finalName>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<configuration>
<excludes>
<exclude>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
</exclude>
</excludes>
</configuration>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-surefire-plugin</artifactId>
<version>2.19.1</version>
</plugin>
<plugin>
<groupId>com.google.cloud.tools</groupId>
<artifactId>appengine-maven-plugin</artifactId>
<version>2.2.0</version>
<configuration>
<deploy.version>1.0</deploy.version>
<project>thehowlingwolfe</project>
<deploy.promote>true</deploy.promote>
<deploy.stopPreviousVersion>true</deploy.stopPreviousVersion>
</configuration>
</plugin>
<plugin>
<groupId>org.eclipse.jetty</groupId>
<artifactId>jetty-maven-plugin</artifactId>
<version>9.3.7.v20160115</version>
</plugin>
</plugins>
</build>
</project>
and my app.yml:
runtime: java
env: flex
handlers:
- url: /.*
script: this field is required, but ignored
health_check:
enable_health_check: False
I don't usually use yaml files but GAE kept giving me exceptions for not having one. I googled to current contents of it, so maybe that is the problem? Anything I should add/remove?
Something else I am missing?
Thanks

Answer 1

It looks like is something related to the pom.xml configuration. Take a look in this sample code where it's important how you declare the projectId.