Nexus not downloading artifacts through Hudson - maven

Question

I'm trying to integrate Hudson with Nexus.
As I build a project without using Nexus, its build is successful.
When I try building it with Nexus, I get the following build errors:
Apache Maven 3.1.1 (0728685237757ffbf44136acec0402957f723d9a; 2013-09-17 12:22:22-0300)
Maven home: /var/lib/hudson/maven/slavebundle/bundled-maven
Java version: 1.7.0_91, vendor: Oracle Corporation
Java home: /usr/lib/jvm/java-1.7.0-openjdk-1.7.0.91.x86_64/jre
Default locale: pt_BR, platform encoding: UTF-8
OS name: "linux", version: "2.6.32-220.el6.x86_64", arch: "amd64", family: "unix"
SLF4J: Class path contains multiple SLF4J bindings.
SLF4J: Found binding in [jar:file:/var/lib/hudson/maven/slavebundle/lib/maven3-eventspy-runtime.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: Found binding in [jar:file:/var/lib/hudson/maven/slavebundle/bundled-maven/lib/slf4j-simple-1.7.5.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: See http://www.slf4j.org/codes.html#multiple_bindings for an explanation.
[DEBUG] Connected to remote
[INFO] o.h.m.e.h.SettingsBuildingRequestHandler - Using settings document ID: ff56412a-102c-4256-80bf-f234990c91ba
[INFO] Scanning for projects...
[INFO]
[INFO] ------------------------------------------------------------------------
[INFO] Building Project
[INFO] ------------------------------------------------------------------------
Downloading: http://localhost:8081/nexus/content/groups/public/org/apache/maven/plugins/maven-clean-plugin/2.5/maven-clean-plugin-2.5.pom
[WARNING] The POM for org.apache.maven.plugins:maven-clean-plugin:jar:2.5 is missing, no dependency information available
Downloading: http://localhost:8081/nexus/content/groups/public/org/apache/maven/plugins/maven-clean-plugin/2.5/maven-clean-plugin-2.5.jar
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 1.378s
[INFO] Finished at: Thu Nov 12 11:37:31 BRST 2015
[INFO] Final Memory: 7M/30M
[INFO] ------------------------------------------------------------------------
[INFO] o.h.m.e.h.MavenExecutionResultHandler - Build failed with exception(s)
[INFO] o.h.m.e.h.MavenExecutionResultHandler - [1] org.apache.maven.plugin.PluginResolutionException: Plugin org.apache.maven.plugins:maven-clean-plugin:2.5 or one of its dependencies could not be resolved: Could not find artifact org.apache.maven.plugins:maven-clean-plugin:jar:2.5 in nexus (http://localhost:8081/nexus/content/groups/public)
[DEBUG] Closing connection to remote
[ERROR] Plugin org.apache.maven.plugins:maven-clean-plugin:2.5 or one of its dependencies could not be resolved: Could not find artifact org.apache.maven.plugins:maven-clean-plugin:jar:2.5 in nexus (http://localhost:8081/nexus/content/groups/public) -> [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/PluginResolutionException
[DEBUG] Waiting for process to finish
[DEBUG] Result: 1
[DEBUG] Skipping watched dependency update for build: Tracker #26 due to result: FAILURE
Finished: FAILURE
And this is my configured Settings on Hudson:
<settings>
<mirrors>
<mirror>
<!--This sends everything else to /public -->
<id>nexus</id>
<mirrorOf>*</mirrorOf>
<url>http://localhost:8081/nexus/content/groups/public</url>
</mirror>
</mirrors>
<profiles>
<profile>
<id>nexus</id>
<!--Enable snapshots for the built in central repo to direct -->
<!--all requests to nexus via the mirror -->
<repositories>
<repository>
<id>central</id>
<url>http://central</url>
<releases><enabled>true</enabled></releases>
<snapshots><enabled>true</enabled></snapshots>
</repository>
</repositories>
<pluginRepositories>
<pluginRepository>
<id>central</id>
<url>http://central</url>
<releases><enabled>true</enabled></releases>
<snapshots><enabled>true</enabled></snapshots>
</pluginRepository>
</pluginRepositories>
</profile>
</profiles>
<activeProfiles>
<!--make the profile active all the time -->
<activeProfile>nexus</activeProfile>
</activeProfiles>
<servers>
<server>
<id>nexus</id>
<username>admin</username>
<password>admin123</password>
</server>
</servers>
</settings>
I don't know why is it not downloading from central repository into the nexus public repository.
Can someone shed some light into this?

Answer 1

I finally solved it. It was throwing as SSL Exception when trying to access the Central Repository.
This exception was automatically blocking my access.
I went to Central Repository > Configuration and changed the Remote Storage Location url to: http://repo.maven.apache.org/maven2/ and right-clicked on Central and clicked Allow Proxy.
It worked like a charm after that.
I hope this helps someone, because I lost almost two days to this.
EDIT (19/11/2015):
If you're running your openjdk using RedHat/CentOS, there's a bug preventing access via SSL, just as pointed by #rseddon in the comments section. The workarounds are here: https://issues.sonatype.org/browse/NEXUS-7999?focusedCommentId=306680&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-306680
If you're in a hurry, this is the one I used:
Add the following line to ${JAVA_HOME}/jre/lib/security/java.security :
jdk.tls.disabledAlgorithms=EC,ECDHE,ECDH
Now I can use the https link on my Central Repo.