How to fix "Either artifact or artifactItems is required" error in MAVEN

Question

my project is a very simple example because I removed all your code to try to find the problem by running the command "mvn dependency: copy -Dcopy.version = 0.0.1-SNAPSHOT".

The point is, I need to package projects to publish .jar on Google Cloud.

Here is the description of the POM´s:

Project: app-java/pom.xml

<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>2.1.7.RELEASE</version>
    <relativePath />
</parent>

<modelVersion>4.0.0</modelVersion>

<groupId>br.com.example</groupId>
<artifactId>ticket</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>pom</packaging>

<name>xxxx</name>
<url>xxxxxr</url>
<description>xxxxxx</description>

<properties>    
</properties>

<modules>
    <module>app</module>
</modules>

<profiles>
    <profile>
        <id>dev</id>
        <modules>
            <module>api</module>
        </modules>
        <activation>
            <activeByDefault>true</activeByDefault>
        </activation>
        <properties>
            <profile.id>dev</profile.id>
            <downloadSources>true</downloadSources>
            <downloadJavadocs>true</downloadJavadocs>
        </properties>
    </profile>
    <profile>
        <id>test</id>
        <activation>
            <activeByDefault>true</activeByDefault>
        </activation>
        <properties>
            <profile.id>test</profile.id>
            <downloadSources>true</downloadSources>
            <downloadJavadocs>true</downloadJavadocs>
        </properties>
    </profile>
    <profile>
        <id>all</id>
        <activation>
            <activeByDefault>true</activeByDefault>
        </activation>
        <properties>
            <profile.id>all</profile.id>
            <downloadSources>true</downloadSources>
            <downloadJavadocs>true</downloadJavadocs>
        </properties>
    </profile>
</profiles>

<build>
    <pluginManagement>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-surefire-plugin</artifactId>
                <version>2.22.0</version>
            </plugin>
        </plugins>
    </pluginManagement>
</build>

Project: app/pom.xml

<parent>
    <groupId>br.com.example</groupId>
    <artifactId>ticket</artifactId>
    <version>0.0.1-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>

<artifactId>app</artifactId>

<build>
    <plugins>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-dependency-plugin</artifactId>
            <version>3.1.1</version>
            <executions>
                <execution>
                    <id>copy-dependencies</id>
                    <phase>package</phase>
                    <goals>
                        <goal>copy-dependencies</goal>
                    </goals>
                    <configuration>
                        <artifactItems>
                            <artifactItem>
                                <groupId>br.com.example</groupId>
                                <artifactId>app</artifactId>
                                <type>jar</type>
                                <overWrite>true</overWrite>
                                <outputDirectory>target/deploy</outputDirectory>
                                <destFileName>app.jar</destFileName>
                            </artifactItem>
                        </artifactItems>
                    </configuration>
                </execution>
            </executions>
        </plugin>
    </plugins>
</build>

Commands executed:

mvn -B versions:set -f app-java/pom.xml -DallowSnapshots=true -DnewVersion=0.0.1-SNAPSHOT -Pall
mvn clean -f app-java/pom.xml install -Pall -Dmaven.application.buildNumber=12
mvn dependency:copy -Dcopy.version=0.0.1-SNAPSHOT

Response:

app-java\app>mvn dependency:copy -Dcopy.version=0.0.1-SNAPSHOT
[INFO] Scanning for projects...
[INFO]
[INFO] -------------------------< br.com.example:app >--------------------------
[INFO] Building app 0.0.1-SNAPSHOT
[INFO] --------------------------------[ jar ]---------------------------------
[INFO]
[INFO] --- maven-dependency-plugin:3.1.1:copy (default-cli) @ app ---
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  2.632 s
[INFO] Finished at: 2019-08-19T22:16:17-03:00
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal org.apache.maven.plugins:maven-dependency-plugin:3.1.1:copy (default-cli) on project app: **Either artifact or artifactItems is required**  -> [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/MojoFailureException
mvn dependency:copy -Dcopy.version=0.0.1-SNAPSHOT

Answer 1

depending what you are doing, if you run mvn install the execution part will be automatically executed and you do not have to run 'mvn dependency:copy'

if you want to run mvn dependency:copy separately, i.e. after running mvn package, then remove execution part. Now it will not be picked up automatically, you have to add mvn dependency: copy

<build>
<plugins>
    <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-dependency-plugin</artifactId>
        <version>3.1.1</version>
                <configuration>
                    <artifactItems>
                        <artifactItem>
                            <groupId>br.com.example</groupId>
                            <artifactId>app</artifactId>
                            <type>jar</type>
                            <overWrite>true</overWrite>
                            <outputDirectory>target/deploy</outputDirectory>
                            <destFileName>app.jar</destFileName>
                        </artifactItem>
                    </artifactItems>
                </configuration>
    </plugin>
</plugins>

Answer 2

You configured the execution of dependency:copy-dependencies, but you also call dependency:copy on command line. This does not have a configuration in the POM and therefore misses the artifactItems entries.