using m2e, getting noclassdeffound error when running maven build compile

Question

I'm new to Maven and this is a followup to a previous question ( Attempting to build Mave (with M2E) getting classdef error ) the gentleman who answered me told me to check dependencies and I noticed there was apparently one conflict. So I figured out how to exclude the SLF4J 1.7.5 from logback and just use the 1.7.2 version from guava (since I couldn't figure out how to exclude from a dependency of a dependency...) and I'm still getting the same error I was before, yet when I run the dependency command again there doesn't seem to be any errors:

[INFO] --- maven-dependency-plugin:2.8:tree (default-cli) @ auth ---
[INFO] com.v2.auth:auth:jar:0.0.1-SNAPSHOT
[INFO] +- junit:junit:jar:3.8.1:test
[INFO] +- ch.qos.logback:logback-classic:jar:1.0.13:compile
[INFO] |  \- ch.qos.logback:logback-core:jar:1.0.13:compile
[INFO] +- com.jolbox:bonecp:jar:0.8.0.RELEASE:compile
[INFO] |  +- com.google.guava:guava:jar:15.0:compile
[INFO] |  \- org.slf4j:slf4j-api:jar:1.7.2:compile
[INFO] \- mysql:mysql-connector-java:jar:5.1.6:compile
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 1.346s
[INFO] Finished at: Wed Jan 29 15:53:43 EST 2014
[INFO] Final Memory: 12M/149M

for reference the error I'm getting is:

Exception in thread "main" java.lang.NoClassDefFoundError: com/ning/http/client/AsyncHttpProvider
at org.sonatype.aether.connector.async.AsyncRepositoryConnectorFactory.newInstance(AsyncRepositoryConnectorFactory.java:106)
at org.sonatype.aether.impl.internal.DefaultRemoteRepositoryManager.getRepositoryConnector(DefaultRemoteRepositoryManager.java:346)
at org.sonatype.aether.impl.internal.DefaultArtifactResolver.resolve(DefaultArtifactResolver.java:453)
at org.sonatype.aether.impl.internal.DefaultArtifactResolver.resolveArtifacts(DefaultArtifactResolver.java:216)
at org.sonatype.aether.impl.internal.DefaultArtifactResolver.resolveArtifact(DefaultArtifactResolver.java:193)
at org.apache.maven.repository.internal.DefaultArtifactDescriptorReader.loadPom(DefaultArtifactDescriptorReader.java:281)
at org.apache.maven.repository.internal.DefaultArtifactDescriptorReader.readArtifactDescriptor(DefaultArtifactDescriptorReader.java:186)
at org.sonatype.aether.impl.internal.DefaultRepositorySystem.readArtifactDescriptor(DefaultRepositorySystem.java:279)
at org.apache.maven.plugin.internal.DefaultPluginDependenciesResolver.resolve(DefaultPluginDependenciesResolver.java:115)
at org.apache.maven.plugin.internal.DefaultMavenPluginManager.getPluginDescriptor(DefaultMavenPluginManager.java:142)
at org.apache.maven.plugin.DefaultBuildPluginManager.loadPlugin(DefaultBuildPluginManager.java:59)
at org.apache.maven.plugin.prefix.internal.DefaultPluginPrefixResolver.resolveFromProject(DefaultPluginPrefixResolver.java:139)
at org.apache.maven.plugin.prefix.internal.DefaultPluginPrefixResolver.resolveFromProject(DefaultPluginPrefixResolver.java:122)
at org.apache.maven.plugin.prefix.internal.DefaultPluginPrefixResolver.resolve(DefaultPluginPrefixResolver.java:86)
at org.apache.maven.lifecycle.internal.MojoDescriptorCreator.findPluginForPrefix(MojoDescriptorCreator.java:262)
at org.apache.maven.lifecycle.internal.MojoDescriptorCreator.getMojoDescriptor(MojoDescriptorCreator.java:222)
at org.apache.maven.lifecycle.internal.DefaultLifecycleTaskSegmentCalculator.calculateTaskSegments(DefaultLifecycleTaskSegmentCalculator.java:106)
at org.apache.maven.lifecycle.internal.DefaultLifecycleTaskSegmentCalculator.calculateTaskSegments(DefaultLifecycleTaskSegmentCalculator.java:86)
at org.apache.maven.lifecycle.internal.LifecycleStarter.execute(LifecycleStarter.java:98)
at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:320)
at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:156)
at org.apache.maven.cli.MavenCli.execute(MavenCli.java:537)
at org.apache.maven.cli.MavenCli.doMain(MavenCli.java:196)
at org.apache.maven.cli.MavenCli.main(MavenCli.java:141)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced(Launcher.java:290)
at org.codehaus.plexus.classworlds.launcher.Launcher.launch(Launcher.java:230)
at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode(Launcher.java:409)
at org.codehaus.plexus.classworlds.launcher.Launcher.main(Launcher.java:352)
Caused by: java.lang.ClassNotFoundException: com.ning.http.client.AsyncHttpProvider
at org.codehaus.plexus.classworlds.strategy.SelfFirstStrategy.loadClass(SelfFirstStrategy.java:50)
at org.codehaus.plexus.classworlds.realm.ClassRealm.loadClass(ClassRealm.java:244)
at org.codehaus.plexus.classworlds.realm.ClassRealm.loadClass(ClassRealm.java:230)
... 32 more

So I guess my question is where do I go from here? I've attempted to find any more information about this error from google or other SO questions but everyone just keeps saying its because its missing a class, which is obvious but this only started happening after I started using maven so that must mean there's a dependency I'm missing? What would I need to include to stop this issue?

Also a side note: the project builds when I run the mvn compile via command line on the correct folder, of course when running it it claims there is a cert issue, even though its the exact same code that was used before I switched to maven, which worked perfectly fine.

also if needed here is my POM for this project:

<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>com.v2.auth</groupId>
  <artifactId>auth</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <packaging>jar</packaging>

  <name>auth</name>
  <url>http://maven.apache.org</url>

  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
  </properties>

  <dependencies>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>3.8.1</version>
      <scope>test</scope>
    </dependency>
    <dependency>
      <groupId>ch.qos.logback</groupId>
      <artifactId>logback-classic</artifactId>
      <version>1.0.13</version>
      <exclusions>
        <exclusion>  <!-- declare the exclusion here -->
          <groupId>org.slf4j</groupId>
          <artifactId>slf4j-api</artifactId>
        </exclusion>
      </exclusions>
    </dependency>
    <dependency>
      <groupId>com.jolbox</groupId>
      <artifactId>bonecp</artifactId>
      <version>0.8.0.RELEASE</version>
    </dependency>
    <dependency>
      <groupId>mysql</groupId>
      <artifactId>mysql-connector-java</artifactId>
      <version>5.1.6</version>
    </dependency>
  </dependencies>

  <build>
   <plugins>
     <plugin>
          <artifactId>maven-assembly-plugin</artifactId>
          <configuration>
            <archive>
              <manifest>
                <mainClass>com.v2.auth.App</mainClass>
              </manifest>
            </archive>
            <descriptorRefs>
              <descriptorRef>jar-with-dependencies</descriptorRef>
            </descriptorRefs>
          </configuration>
          <executions>
            <execution>
              <id>make-assembly</id> <!-- this is used for inheritance merges -->
              <phase>package</phase> <!-- bind to the packaging phase -->
              <goals>
                <goal>single</goal>
              </goals>
            </execution>
          </executions>
        </plugin>
        <plugin>
          <groupId>org.apache.maven.plugins</groupId>
          <artifactId>maven-compiler-plugin</artifactId>
          <version>3.0</version>
          <configuration>
           <source>1.7</source>
           <target>1.7</target>
          </configuration>
        </plugin>
    </plugins>
  </build>
</project>

I'm sorry if this is just a stupid obvious question but I'm at my wits end trying to figure this out on my own.

Answer 1

This has nothing to do with your code or its dependencies. Looking at the posted stacktrace, it's clear that this is a problem with the m2e feature, specifically the "async-http-client" plugin from Sonatype. Reinstall m2e in Eclipse. The following screenshot shows m2e's plugins in my eclipse. Pleas note the the first item in the list.