Problem integrating web3j into maven clean install

[andras-ballai]

I have a multi-module maven project where I want to generate java wrappers from .sol files, to achieve this I'm using web3j's maven plugin. Here are the (relevant sections of the) poms:

main pom.xml:

<build>
	<plugins>
		<plugin>
			<groupId>org.web3j</groupId>
			<artifactId>web3j-maven-plugin</artifactId>
			<version>4.9.4</version>
			<executions>
				<execution>
					<goals>
						<goal>generate-sources</goal>
					</goals>
				</execution>
			</executions>
		</plugin>
	</plugins>
</build>

child pom.xml:

<build>
	<plugins>
		<plugin>
			<groupId>org.web3j</groupId>
			<artifactId>web3j-maven-plugin</artifactId>
			<executions>
				<execution>
					<goals>
						<goal>generate-sources</goal>
					</goals>
				</execution>
			</executions>
			<configuration>
				<soliditySourceFiles>
					<directory>${project.basedir}/src/main/resources/solidity</directory>
					<includes>
						<include>**/*.sol</include>
					</includes>
				</soliditySourceFiles>
				<packageName>org.example.project-name.wrappers</packageName>
				<outputDirectory>
					<java>${project.build.directory}/generated-sources/web3j/java</java>
				</outputDirectory>
			</configuration>
		</plugin>
	</plugins>
</build>

I'm build the project with maven with the following command: call mvn clean -U install.
The files do generate, and in the correct location, but when maven begins the compile phase of install it runs into the following error:

Compilation failure
[ERROR] /C:/source/project/project-name/src/main/java/org/example/child/TestFile.java:[4,51] 
package org.example.project-name.wrappers does not exist

TestFile is an empty file that tries to import one of the generated files.

I also have an openapi code generator plugin, it does generate files properly, and I run into no issues when importing those.
I didn't find any configuration options in the web3j plugin that I missed and I also didn't find any way to help mvn install or mvn compile consider the directory in which the wrappers are generated.

I tried manually extracting the bundled calls that install makes and manually interjecting the web3j:generate-sources:

 call mvn clean
 call mvn web3j:generate-sources
 call mvn process-resources
 call mvn compile
 call mvn process-test-resources
 call mvn test
 call mvn package
 call mvn install
 call mvn deploy

But this too fails at compile. I'm assuming that the web3j plugin doesn't update a variable storing all generated sources, but that's just a guess and I don't know how I would fix that.

[andras-ballai]

I managed to solve the issue using org.codehaus:build-helper-maven-plugin.

I added the plugin to the dependencies of my main pom and the relevant child (I use dependency management), then added the plugin to the child's pom:

<plugin>
	<groupId>org.codehaus.mojo</groupId>
	<artifactId>build-helper-maven-plugin</artifactId>
	<executions>
		<execution>
			<id>add-source</id>
			<phase>generate-sources</phase>
			<goals>
				<goal>add-source</goal>
			</goals>
			<configuration>
				<sources>
					<source>${project.build.directory}/generated-sources/web3j</source>
				</sources>
			</configuration>
		</execution>
	</executions>
</plugin>

I also figured out that my assumption was correct: web3j's plugin does not update the project's sources directory.
I still think that such a basic feature should either be added or its absence should be documented and solutions/workarounds to it mentioned.