Maven Jetty spamming "scanned from multiple location"

Question

So, i'm new using Jetty with Maven, my first project is spamming a hundreds of warnings like

[WARNING] com.google.inject.util.Providers scanned from multiple locations:
jar:file:///C:/Users/pedro/.m2/repository/org/sonatype/sisu/sisu-guice/2.1.7/sisu-guice-2.1.7-noaop.jar!/com/google/inject/util/Providers.class,
jar:file:///C:/Users/pedro/.m2/repository/com/google/inject/guice/4.2.1/guice-4.2.1-no_aop.jar!/com/google/inject/util/Providers.class

I found some answers on the internet that says it is because there is duplicate dependencies, and I have to fix it on the pom.xml and .classpath, but I do not have duplicate dependencies and don't know how to fix on the .classpath.

Someone knows how can i fix it?

score 1 · Answer 1 · answered Jun 24 '20 at 20:13

That's a legitimate warning.

The bytecode/annotation scanning found that you have multiple locations for the class com.google.inject.util.Providers.

You have 2 different versions of guice coming from 2 different locations.

With this scenario, the Classloader sometimes uses sisu-guice-2.1.7-noaop.jar and sometimes it's using guice-4.2.1-no_aop.jar for that class.

You have a situation where your runtime is unpredictable.

Each time you run the application a different behavior can occur.

Seeing as these are coming from your maven infrastructure, I would recommend running one of the duplicate class finder maven plugins to clean up your dependency tree.

See other question about Find duplicated classes in classpath

score 0 · Accepted Answer · answered Jun 25 '20 at 12:04

I solved it removing the dependency

<dependency>
  <groupId>org.eclipse.jetty</groupId>
  <artifactId>jetty-maven-plugin</artifactId>
  <version>9.4.30.v20200611</version>
</dependency>

and keeping only the plugin

<plugin>
  <groupId>org.eclipse.jetty</groupId>
  <artifactId>jetty-maven-plugin</artifactId>
  <version>9.4.30.v20200611</version>
</plugin>

Maven Jetty spamming "scanned from multiple location"

2 Answers2