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Maven JavaDoc listed classes twice

I am using the javadoc maven plugin and it creates the correct javadoc package, but all classes are created twice.
Maven dependency:
<dependency>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-javadoc-plugin</artifactId>
<version>3.3.0</version>
</dependency>
My build code
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-javadoc-plugin</artifactId>
<executions>
<execution>
<id>attach-javadocs</id>
<goals>
<goal>jar</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</build>
Can anyone help me please, what am I missing here?
command usage for doc generation
mvn clean install -Dresources="FirstProject/example_API"

I noticed the same problem and came upon a solution after enabling debug on the maven-javadoc-plugin maven plugin and seeing what it's doing. Specifically setting the sourcepath as shown below fixed the double listing problem for me and I've tried this on multiple version of Corretto 8 as well as Temurin 8. All had the double listing problem because it's an issue with the javadoc tool itself but setting the sourcepath manually fixed it for me.
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-javadoc-plugin</artifactId>
<version>3.3.1</version>
<configuration>
<debug>true</debug>
<sourcepath>${basedir}/src/main/java</sourcepath>
</configuration>
<executions>
<execution>
<id>attach-javadocs</id>
<goals>
<goal>jar</goal>
</goals>
</execution>
</executions>
</plugin>

There's a bug in recent versions of the Maven Javadoc Plugin. The bug is known as MJAVADOC-700. It is dead easy to reproduce.
Downgrading to version 3.2.0 of the plugin fixes the problem. Setting the sourcepath explicitly is an alternative fix.

How to make apt-maven-plugin work with java 8

I am migrating from java 6 to java 8. I have a maven project and it has apt-maven-plugin which is not running on jdk 1.8. Do we have a workaround or an alternate to make it work with java 8? Is it possible to run apt-maven-plugin with java 8??
Please find below the maven entry:
<plugin>
<groupId>org.codehaus.mojo</groupId>
<artifactId>apt-maven-plugin</artifactId>
<version>1.0-alpha-3</version>
<configuration>
<factory>
com.emc.tsg.common.xml.ABCGenerator
</factory>
<includes>
<include>**/model/*.java</include>
</includes>
</configuration>
<executions>
<execution>
<goals>
<goal>process</goal>
</goals>
</execution>
</executions>
</plugin>
and i have changed the maven tools.jar dependency for java 8 as:
<dependency>
<groupId>com.sun</groupId>
<artifactId>tools</artifactId>
<version>1.8</version>
<scope>system</scope>
<systemPath>${java.home}/../lib/tools.jar</systemPath>
</dependency>
I have changed the java version as:
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<configuration>
<source>1.8</source>
<target>1.8</target>
<optimize>true</optimize>
<debug>false</debug>
</configuration>
</plugin>
When i am trying to run mvn compile, i am getting apt compiler not found error. I think in jdk tools.jar there is no apt class unlike java 6 hence wondering if at all its possible to achieve this in java 8?

How to resolve maven EnforcedBytecodeVersion failure?

When trying to run maven enforcer getting a failure due to some classes conforming to 1.9 where as the entire project is confine dto 1.8. Following is the stack trace of the log. That specific dependency is being pulled by a different jar which can't be excluded as it has compile time dependency.
[INFO] Checking unresolved references to org.codehaus.mojo.signature:java18:1.0
[INFO] Restricted to JDK 1.8 yet javax.json.bind:javax.json.bind-api:jar:1.0:compile contains module-info.class targeted to JDK 1.9
[WARNING] Rule 14: org.apache.maven.plugins.enforcer.EnforceBytecodeVersion failed with message:
Found Banned Dependency: javax.json.bind:javax.json.bind-api:jar:1.0

It seemed to be that you misunderstand the intention of enforceBytecodeversion...It will check all dependencies if they use byte code for a more recent version as stated which means higher than JDK 8 just lifting the maxJdkVersion is not solving the problem. The problem is related to the dependencies you are using ....
The dependency: javax.json.bin:javax.json.bind-api
contains a `module-info.class` file which is related to JDK 9 ...
If you are sure all code in that dependency does not use JDK 9 specific things you have to exclude module-info.class from checking in enforcer rules...
Update:
This can be achieved by using the following:
<project>
[...]
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-enforcer-plugin</artifactId>
<version>3.0.0-M1</version>
<executions>
<execution>
<id>enforce-bytecode-version</id>
<goals>
<goal>enforce</goal>
</goals>
<configuration>
<rules>
<enforceBytecodeVersion>
<maxJdkVersion>1.8</maxJdkVersion>
<ignoreClasses>
<ignoreClass>module-info</ignoreClass>
</ignoreClasses>
</enforceBytecodeVersion>
</rules>
</configuration>
</execution>
</executions>
<dependencies>
<dependency>
<groupId>org.codehaus.mojo</groupId>
<artifactId>extra-enforcer-rules</artifactId>
<version>1.0-beta-9</version>
</dependency>
</dependencies>
</plugin>
</plugins>
</build>
[...]
</project>

By overriding the target bytecode to 1.9 in the child pom was able to resolve the enforcer issue as follows.
<plugin>
<artifactId>maven-enforcer-plugin</artifactId>
<executions>
<execution>
<goals>
<goal>enforce</goal>
</goals>
<configuration>
<rules>
<enforceBytecodeVersion>
<maxJdkVersion>1.9</maxJdkVersion>
</enforceBytecodeVersion>
</rules>
<fail>true</fail>
</configuration>
</execution>
</executions>
</plugin>

Gatling Maven plugin and Maven 3.3.3

For some reason SLF4J is removed from the classpath when you use Maven 3.3.3. I found some links with some info about it but it's not clear to me how to fix this issue.
https://github.com/gatling/gatling/issues/2632
https://issues.apache.org/jira/browse/MNG-5791#add-comment
I tried adding the dependency to the plugin itself like this:
<plugin>
<groupId>io.gatling</groupId>
<artifactId>gatling-maven-plugin</artifactId>
<version>${gatling-plugin.version}</version>
<dependencies>
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-api</artifactId>
<version>1.7.12</version>
</dependency>
</dependencies>
<executions>
<execution>
<id>performance-test-1</id>
<phase>test</phase>
<goals>
<goal>execute</goal>
</goals>
<configuration>
.....
</configuration>
</execution>
</executions>
</plugin>
But that doesn't seem to work. Does anybody know how to solve this issue?

This compat issue has been fixed in 2.1.5.
Just upgrade.

Running JDK8 for aspectj

I am trying to run aspectj-maven plugin with JDK8. But it is giving errors like
"The type java.lang.CharSequence cannot be resolved. It is indirectly referenced from required .class files"
Any help on how to resolve, or if the aspectj-maven-plugin supports JDK8. I am using 1.6 version of aspectj--maven-plugin.

I had to achieve the same and I drove crazy trying to figure out this, fortunately I could solve it and here I give you what I did:
To use aspectj-maven-plugin with Java 8 you need version aspectj-maven-plugin 1.7 (Note that aspectj-maven-plugin 1.6 works for Java 7).
So, the maven plugin configuration needs to be:
<!-- AspectJ configuration -->
<plugin>
<groupId>org.codehaus.mojo</groupId>
<artifactId>aspectj-maven-plugin</artifactId>
<version>1.7-SNAPSHOT</version>
<configuration>
<complianceLevel>1.8</complianceLevel>
<source>1.8</source>
<target>1.8</target>
</configuration>
<executions>
<execution>
<goals>
<goal>compile</goal>
<goal>test-compile</goal>
</goals>
</execution>
</executions>
</plugin>
By the way, the aspectJ jars needed are:
<!-- Spring AOP + AspectJ -->
<dependency>
<groupId>org.aspectj</groupId>
<artifactId>aspectjrt</artifactId>
<version>1.8.1</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-aop</artifactId>
<version>1.8.1</version>
</dependency>
<dependency>
<groupId>org.aspectj</groupId>
<artifactId>aspectjweaver</artifactId>
<version>1.8.1</version>
</dependency>
And the most important thing I've struggled was that you need to install the aspectj-maven-plugin 1.7 jar manually into your pom.xml since this jar aren't on maven repo yet.
You can get it from Haus Jira (look at the Attachment section):
https://jira.codehaus.org/browse/MASPECTJ-131
Btw, once you download it an copy it to your repo you need to create your own aspectj-maven-plugin-1.7-SNAPSHOT.pom file within the corresponding directory. You can copy it from version 1.6 BUT ensure you modify the following content:
<version>1.7-SNAPSHOT</version>
<properties>
<aspectjVersion>1.8.1</aspectjVersion>
<mavenVersion>2.2.1</mavenVersion>
<changesPluginVersion>2.9</changesPluginVersion>
</properties>
That's all here you go, hope to help.

You don't need 1.7-SNAPSHOT for that. I have this snippent in POM and everything works:
<plugin>
<groupId>org.codehaus.mojo</groupId>
<artifactId>aspectj-maven-plugin</artifactId>
<version>1.5</version>
<executions>
<execution>
<goals>
<goal>compile</goal>
</goals>
</execution>
</executions>
<configuration>
<source>1.8</source>
<target>1.8</target>
<complianceLevel>1.8</complianceLevel>
<showWeaveInfo>true</showWeaveInfo>
</configuration>
<dependencies>
<dependency>
<groupId>org.aspectj</groupId>
<artifactId>aspectjrt</artifactId>
<version>1.8.1</version>
</dependency>
<dependency>
<groupId>org.aspectj</groupId>
<artifactId>aspectjtools</artifactId>
<version>1.8.1</version>
</dependency>
</dependencies>
</plugin>

Another way to solve this problem is to downgrade JDK level to 1.7. JDK 1.7 works well with aspectj-maven-plugin of versions 1.4 - 1.6.
Here is a screenshot showing how to change JDK level in IntelliJ IDEA project:
Set Project SDK to 1.7. See documentation for more details.