Generate the JPA metamodel files using maven-processor-plugin - What is a convenient way for re-generation?

Question

I am trying to use maven-processor-plugin for generating JPA metamodel java files and I set up my pom.xml as belows.

<plugin>
        <artifactId>maven-compiler-plugin</artifactId>
        <configuration>
            <source>1.8</source>
            <target>1.8</target>
            <compilerArgument>-proc:none</compilerArgument>
        </configuration>
    </plugin>
    <plugin>
        <groupId>org.bsc.maven</groupId>
        <artifactId>maven-processor-plugin</artifactId>
        <executions>
            <execution>
                <id>process</id>
                <goals>
                    <goal>process</goal>
                </goals>
                <phase>generate-sources</phase>
                <configuration>
                    <!-- source output directory -->
                    <outputDirectory>${basedir}/src/main/java</outputDirectory>
                    <processors>
                        <processor>org.hibernate.jpamodelgen.JPAMetaModelEntityProcessor</processor>
                    </processors>
                    <overwrite>true</overwrite>
                </configuration>
            </execution>
        </executions>
    </plugin>

Actually, I want to generate metamodel files (Entity_.java) to the same packages of their corresponding entities (Entity.java). Hence, I set up outputDirectory in the plugin as

<outputDirectory>${basedir}/src/main/java</outputDirectory>

The first time of running is ok, but from later times when performing the metamodel java files re-generation, the plugin always turns out an error about file duplication.

My Question is - Is there any way to config the plugin so that it could overwrite the existing files during re-generation?

In fact, to work around

1. I must delete all generated files before any re-generation.
2. I could point the outputDirectory to a different folder in /target, this location will be clean everytime Maven run, but this leads to manually copy generated metamodel files to source folder for update after re-generation.

Both of these are very inconvenient and I hope you guys could show me a proper solution.

Answer 1

In case you your have another annotation processor used during compilation (like lombok) you might run into following error (depite having hibernate-jpamodelgen added as dependency):

[INFO] -------------------------------------------------------------
[ERROR] COMPILATION ERROR :
[INFO] -------------------------------------------------------------
[ERROR] /your/not/CompilableClass:[5,68] cannot find symbol
  symbol:   class YouEntity_
  location: package your.not
[INFO] 1 error

In this case you need to declare both annotation processors directly for your compiler plugin (for both lombok and hibernate):

            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.8.1</version>
                <configuration>
                    <source>11</source>
                    <target>11</target>
                    <annotationProcessorPaths>
                        <path>
                            <groupId>org.projectlombok</groupId>
                            <artifactId>lombok</artifactId>
                            <version>${lombok.version}</version>
                        </path>
                        <path>
                            <groupId>org.hibernate</groupId>
                            <artifactId>hibernate-jpamodelgen</artifactId>
                            <version>${hibernate-jpamodelgen.version}</version>
                        </path>
                    </annotationProcessorPaths>
                </configuration>
            </plugin>