maven-code-gen-example/org.example.codegen/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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>

  <groupId>org.example</groupId>
  <artifactId>org.example.codegen</artifactId>
  <name>Example Code Generator</name>

  <version>0.0.1-SNAPSHOT</version>

  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <maven.compiler.version>3.12.1</maven.compiler.version>
    <build.helper.maven.version>3.5.0</build.helper.maven.version>
    <java.version>17</java.version>
    <maven.clean.version>3.3.2</maven.clean.version>
    <exec.maven.version>3.2.0</exec.maven.version>
  </properties>

  <build>
    <sourceDirectory>src/main/java</sourceDirectory>
    <plugins>
      <plugin>
        <artifactId>maven-clean-plugin</artifactId>
        <version>${maven.clean.version}</version>
        <configuration>
          <filesets>
            <fileset>
              <directory>gen</directory>
            </fileset>
          </filesets>
        </configuration>
      </plugin>

      <plugin>
        <artifactId>maven-compiler-plugin</artifactId>
        <version>${maven.compiler.version}</version>
        <configuration>
          <release>${java.version}</release>
        </configuration>
        <executions>
          <execution>
            <id>pre-compile</id>
            <phase>generate-sources</phase>
            <goals>
              <goal>compile</goal>
            </goals>
          </execution>
        </executions>
      </plugin>

      <plugin>
        <groupId>org.codehaus.mojo</groupId>
        <artifactId>build-helper-maven-plugin</artifactId>
        <version>${build.helper.maven.version}</version>
        <executions>
          <execution>
            <id>add-sources</id>
            <goals>
              <goal>add-source</goal>
            </goals>
            <configuration>
              <sources>
                <source>gen/</source>
              </sources>
            </configuration>
          </execution>
        </executions>
      </plugin>

      <plugin>
        <groupId>org.codehaus.mojo</groupId>
        <artifactId>exec-maven-plugin</artifactId>
        <version>${exec.maven.version}</version>
        <executions>
          <execution>
            <phase>process-sources</phase>
            <goals>
              <goal>java</goal>
            </goals>
            <configuration>
              <mainClass>org.example.codegen.CodeGenerator</mainClass>
            </configuration>
          </execution>
        </executions>
      </plugin>

    </plugins>
  </build>
</project>