Heroku Springboot Err: Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.8.1:testCompile - reactjs

Question

I am trying to get my Springboot Backend application to compile on Heroku.
I get the message: Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.8.1:testCompile
I am totally lost and in the weeds on this.
Any help would be appreciated.
I do not even know how or where to add the -e or -X switch (referenced below).
Here is the applicable portion of the log and my POM file.
[INFO] Downloaded from central: https://repo.maven.apache.org/maven2/com/thoughtworks/qdox/qdox/2.0-M9/qdox-2.0-M9.jar (317 kB at 10 MB/s)
[INFO] Nothing to compile - all classes are up to date
[INFO]
[INFO] --- maven-resources-plugin:3.2.0:testResources (default-testResources) # budget-backend ---
[INFO] Using 'UTF-8' encoding to copy filtered resources.
[INFO] Using 'UTF-8' encoding to copy filtered properties files.
[INFO] skip non existing resourceDirectory /tmp/build_edc50946/src/test/resources
[INFO]
[INFO] --- maven-compiler-plugin:3.8.1:testCompile (default-testCompile) # budget-backend ---
[INFO] Changes detected - recompiling the module!
[INFO] Compiling 1 source file to /tmp/build_edc50946/target/test-classes
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 9.635 s
[INFO] Finished at: 2022-03-07T15:09:33Z
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.8.1:testCompile (default-testCompile) on project budget-backend: Fatal error compiling: invalid target release: 11 -> [Help 1]
[ERROR]
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR]
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/MojoExecutionException
! ERROR: Failed to build app with Maven
<?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>2.5.0</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>net.javaguides</groupId>
<artifactId>budget-backend</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>budget-backend</name>
<description>Demo project for Spring Boot</description>
<properties>
<java.version>11</java.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-devtools</artifactId>
<scope>runtime</scope>
<optional>true</optional>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>
I added a system.properties file with 'java.runtime.version=11' and the error message from Heroku now says:
Execution repackage of goal org.springframework.boot:spring-boot-maven-plugin:2.5.0:repackage failed: Unable to find main class
Did I make things worse or am I getting closer?

Answer 1

Problem solved. I do not understand why, but it compiles on Heroku now.
I added a system.properties file with the following entry
java.runtime.version=11.
I also changed the POM to read
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<configuration>
<skip>true</skip>
</configuration>
<executions>
<execution>
<phase>none</phase>
</execution>
</executions>
</plugin>
</plugins>