最近使用maven+tycho出现问题，需要探讨下。

heriane 2016-04-05 07:25:58

<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>tycho_example</groupId>  

 <artifactId>com.codeandme.tycho.plugin</artifactId>  

 <version>1.0.0-SNAPSHOT</version>  

 <packaging>eclipse-plugin</packaging>  

  

 <properties>  

  <tycho.version>0.22.0</tycho.version>  

 </properties>  

  

 <repositories>  

  <!-- add Luna repository to resolve dependencies -->  

  <repository>  

   <id>Luna</id>  

   <layout>p2</layout>  

   <url>http://download.eclipse.org/releases/luna/</url>  

  </repository>  

 </repositories>  

  

 <build>  

  <plugins>  

   <plugin>  

    <!-- enable tycho build extension -->  

    <groupId>org.eclipse.tycho</groupId>  

    <artifactId>tycho-maven-plugin</artifactId>  

    <version>${tycho.version}</version>  

    <extensions>true</extensions>  

   </plugin>  

  </plugins>  

 </build>  

</project>

上面代码中：
<properties>
<tycho.version>0.22.0</tycho.version>
</properties>
这个版本信息如何定义的？
我按照这个文档：http://chnic.iteye.com/blog/2201139
但是开发中发现异常

Project build error: Unresolveable build extension: Plugin org.eclipse.tycho:tycho-maven-plugin:0.22.0 or one of its dependencies could not be resolved: The 

 following artifacts could not be resolved: org.sonatype.sisu:sisu-guice:jar:noaop:2.1.7, org.codehaus.plexus:plexus-interpolation:jar:1.14, 

 org.sonatype.plexus:plexus-sec-dispatcher:jar:1.3, org.sonatype.plexus:plexus-cipher:jar:1.7, org.codehaus.plexus:plexus-utils:jar:3.0.7, 

 org.codehaus.plexus:plexus-archiver:jar:2.2, org.codehaus.plexus:plexus-io:jar:2.0.5, org.eclipse.tycho:org.eclipse.osgi.compatibility.state:jar:

 1.0.0.v20140403-1907, org.eclipse.tycho:sisu-equinox-embedder:jar:0.22.0, org.eclipse.tycho:org.eclipse.osgi:jar:3.10.0.v20140606-1445, org.eclipse.tycho:sisu-

 equinox-api:jar:0.22.0, org.eclipse.tycho:tycho-metadata-model:jar:0.22.0, de.pdark:decentxml:jar:1.3, org.eclipse.tycho:tycho-embedder-api:jar:0.22.0, 

 org.eclipse.tycho:org.eclipse.tycho.embedder.shared:jar:0.22.0, org.eclipse.tycho:org.eclipse.tycho.core.shared:jar:0.22.0, org.eclipse.tycho:tycho-p2-facade:jar:

 0.22.0, org.eclipse.tycho:org.eclipse.tycho.p2.resolver.shared:jar:0.22.0, org.eclipse.tycho:org.eclipse.tycho.p2.tools.shared:jar:0.22.0: Failure to transfer 

 org.sonatype.sisu:sisu-guice:jar:noaop:2.1.7 from http://repo.maven.apache.org/maven2 was cached in the local repository, resolution will not be reattempted 

 until the update interval of central has elapsed or updates are forced. Original error: Could not transfer artifact org.sonatype.sisu:sisu-guice:jar:noaop:2.1.7 

 from/to central (http://repo.maven.apache.org/maven2): The operation was cancelled.

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