Maven: Non Existing Library jdk.tools.jar

The Problem
Today,after add some dependencies to maven,  I found that maven refuses to compile. In Problems view, it shows error:
The container 'Maven Dependencies' references non existing library 'C:\Users\administrator\.m2\repository\jdk\tools\jdk.tools\1.6\jdk.tools-1.6.jar'

Check my pom.xml, there is no direct dependency of jdk.tools-1.6.jar, then use maven dependency:tree tool to figure out which lib indirectly depends on it.
mvn dependency:tree -Dverbose -Dincludes=jdk.tools

[INFO] --- maven-dependency-plugin:2.8:tree (default-cli) @ learningLucene ---

[INFO] org.lifelongprogrammer:learningLucene:jar:1.0

[INFO] \- org.apache.solr:solr-core:jar:4.9.0:compile

[INFO]    \- org.apache.hadoop:hadoop-annotations:jar:2.2.0:compile

[INFO]       \- jdk.tools:jdk.tools:jar:1.7:system

Turn out, solr-code depends on hadoop-annotation which then need jdk.tools.jar.

The Solution

Google search, find this page: 

http://maven.apache.org/general.html#tools-jar-dependency

<dependency>
  <groupId>jdk.tools</groupId>
  <artifactId>jdk.tools</artifactId>
  <scope>system</scope>
  <systemPath>C:/Program Files/Java/jdk1.8.0/lib/tools.jar</systemPath>
  <!-- have to include the version, otherwise eclipse throws exception: 
    Errors running builder 'Maven Project Builder' on project 'learningLucene'. 
    java.lang.NullPointerException -->
  <version>8.0</version>
</dependency>
</dependencies>
<build>
<plugins>
  <plugin>
    <artifactId>maven-compiler-plugin</artifactId>
    <configuration>
      <source>1.8</source>
      <target>1.8</target>
    </configuration>
  </plugin>
</plugins>
</build>