Maven 是 3.1.0。
我在项目的 pom.xml 中使用了versions-maven-plugin:2.2（如下所示）。除了通常的 pom.xml 文件配置之外，我只是在下面显示主要代码快照：
<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>
<artifactId>tools-parent</artifactId>
<version>0.0.7-SNAPSHOT</version>
<packaging>pom</packaging>
<description>
Infrastructure related to the "vapp" and
"deployer" utilities.
</description>
<parent>
<groupId>com.company.product</groupId>
<artifactId>deploy-parent</artifactId>
<version>0.0.6-SNAPSHOT</version>
</parent>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-scm-plugin</artifactId>
<version>1.9.4</version>
<configuration>
<connectionType>connection</connectionType>
</configuration>
</plugin>
<plugin>
<groupId>org.codehaus.mojo</groupId>
<artifactId>versions-maven-plugin</artifactId>
<version>2.2</version>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-enforcer-plugin</artifactId>
<version>1.4</version>
<executions>
<execution>
<!-- Make sure that only non-snapshot versions are used for the dependencies. Only active when property 'snapshotDependencyAllowed' is false. -->
<id>enforce-no-snapshots</id>
<goals>
<goal>enforce</goal>
</goals>
<configuration>
<skip>${snapshotDependencyAllowed}</skip>
<rules>
<requireReleaseDeps>
<message>No Snapshots Allowed!</message>
</requireReleaseDeps>
<requireReleaseVersion>
<message>No Snapshots Allowed!</message>
</requireReleaseVersion>
</rules>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
</project>
现在，当我运行：mvn clean install时，它会成功构建。
注意：在我的项目中，我有一个父部分，我依赖于部署父工件，其组 ID“com.company.product”与我想要的工具父工件（其 pom.xml我已经粘贴在上面）但是 deploy-parent 是另一个存储库/项目的工件。
当我运行：mvn versions:set -DnewVersion=0.0.7时，我收到以下错误消息。
[INFO] ------------------------------------------------------------------------
[INFO] Building tools-parent 0.0.7-SNAPSHOT
[INFO] ------------------------------------------------------------------------
[INFO]
[INFO] --- versions-maven-plugin:2.2:set (default-cli) @ tools-parent ---
[INFO] Searching for local aggregator root...
[INFO] Local aggregation root: /user/home/u100123/giga/tools
[INFO] Processing change of com.company.product:tools-parent:0.0.7-SNAPSHOT -> 0.0.7
[INFO] ------------------------------------------------------------------------
[INFO] Reactor Summary:
[INFO]
[INFO] tools-parent .................................... FAILURE [1.093s]
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 2.404s
[INFO] Finished at: Fri May 01 20:44:22 GMT-00:00 2015
[INFO] Final Memory: 12M/246M
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal org.codehaus.mojo:versions-maven-plugin:2.2:set (default-cli) on project tools-parent: Execution default-cli of goal org.codehaus.mojo:versions-maven-plugin:2.2:set failed. NullPointerException -> [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/PluginExecutionException
现在，当我将versions-maven-plugin版本改回2.1（我之前使用的）时，上面的mvn版本：set -DnewVersion = 0.0.7命令成功运行并且pom.xml文件成功更改为<version>0.0.7</version>对于工具父工件。
对于 2.2 版，它给了我错误，而不是将版本更改为 0.0.7。
- 2.2失败的任何原因？可以做些什么来解决它？