Maven 4: Error resolving artifacts in flatten-maven-plugin #495
Description
The following example pom.xml produces an an error in Maven 4 with the flatten-maven-plugin, but not in Maven 3:
<?xml version="1.0" encoding="UTF-8"?>
<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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>foo</groupId>
<artifactId>bar</artifactId>
<version>1.0.0-SNAPSHOT</version>
<packaging>jar</packaging>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
</properties>
<build>
<plugins>
<plugin>
<groupId>org.codehaus.mojo</groupId>
<artifactId>flatten-maven-plugin</artifactId>
<version>1.7.3</version>
<configuration>
<flattenDependencyMode>all</flattenDependencyMode>
</configuration>
</plugin>
</plugins>
</build>
<dependencies>
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-databind</artifactId>
<version>2.20.1</version>
</dependency>
</dependencies>
</project>Maven 4.0.0-rc-5:
$ mvn flatten:flatten
[INFO] Scanning for projects...
[INFO] Loaded 21643 auto-discovered prefixes for remote repository central (prefixes-central.txt)
Downloading from central: https://repo.maven.apache.org/maven2/org/apache/maven/plugins/maven-metadata.xml
Downloading from central: https://repo.maven.apache.org/maven2/org/codehaus/mojo/maven-metadata.xml
Downloaded from central: https://repo.maven.apache.org/maven2/org/apache/maven/plugins/maven-metadata.xml (14 kB at 36.9 kB/s)
Downloaded from central: https://repo.maven.apache.org/maven2/org/codehaus/mojo/maven-metadata.xml (21 kB at 53.2 kB/s)
[INFO]
[INFO] -------------------------------------------------------< foo:bar >--------------------------------------------------------
[INFO] Building bar 1.0.0-SNAPSHOT
[INFO] from pom.xml
[INFO] ---------------------------------------------------------[ jar ]----------------------------------------------------------
[INFO]
[INFO] --- flatten:1.7.3:flatten (default-cli) @ bar ---
[INFO] Generating flattened POM of project foo:bar:jar:1.0.0-SNAPSHOT...
[INFO] Artifact com.fasterxml.jackson:jackson-base:pom:2.20.1 is present in the local repository, but cached from a remote repository ID that is unavailable in current build context, verifying that is downloadable from [central-snapshots (https://central.sonatype.com/repository/maven-snapshots, default, snapshots)]
[INFO] --------------------------------------------------------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] --------------------------------------------------------------------------------------------------------------------------
[INFO] Total time: 0.756 s
[INFO] Finished at: 2025-11-13T12:57:22-06:00
[INFO] --------------------------------------------------------------------------------------------------------------------------
[ERROR] Failed to execute goal org.codehaus.mojo:flatten-maven-plugin:1.7.3:flatten (default-cli) on project bar: failed to create a clean pom: unable to create flattened dependencies: caught exception when flattening dependencies: Failed to read artifact descriptor for com.fasterxml.jackson.core:jackson-databind::2.20.1: The following artifacts could not be resolved: com.fasterxml.jackson:jackson-base:pom:2.20.1 (present, but unavailable) (remote repositories: central-snapshots (https://central.sonatype.com/repository/maven-snapshots, default, snapshots)): One or more requests failed -> [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 verbose output
[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/MojoExecutionExceptionMaven 3.9.11:
$ mvn flatten:flatten
WARNING: A terminally deprecated method in sun.misc.Unsafe has been called
WARNING: sun.misc.Unsafe::staticFieldBase has been called by com.google.inject.internal.aop.HiddenClassDefiner (file:/Users/ishmael/.sdkman/candidates/maven/current/lib/guice-5.1.0-classes.jar)
WARNING: Please consider reporting this to the maintainers of class com.google.inject.internal.aop.HiddenClassDefiner
WARNING: sun.misc.Unsafe::staticFieldBase will be removed in a future release
[INFO] Scanning for projects...
[INFO]
[INFO] ------------------------------< foo:bar >-------------------------------
[INFO] Building bar 1.0.0-SNAPSHOT
[INFO] from pom.xml
[INFO] --------------------------------[ jar ]---------------------------------
[INFO]
[INFO] --- flatten:1.7.3:flatten (default-cli) @ bar ---
[INFO] Generating flattened POM of project foo:bar:jar:1.0.0-SNAPSHOT...
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 0.132 s
[INFO] Finished at: 2025-11-13T12:58:56-06:00
[INFO] ------------------------------------------------------------------------As per discussions in apache/maven#11436, this appears to be due to an issue in flatten-maven-plugin (see apache/maven#11436 (comment)).