Use maven-toolchains-plugin

This allows to run tests with a specific version of JDK independent from
the one Maven is running with.

com.mountainminds.eclemma.build/pom.xml

@@ -127,6 +127,11 @@
  <artifactId>maven-dependency-plugin</artifactId>
  <version>2.10</version>
  </plugin>
+ <plugin>
+ <groupId>org.apache.maven.plugins</groupId>
+ <artifactId>maven-toolchains-plugin</artifactId>
+ <version>1.1</version>
+ </plugin>
  <plugin>
  <groupId>org.apache.maven.plugins</groupId>
  <artifactId>maven-jarsigner-plugin</artifactId>
@@ -363,6 +368,39 @@
  </plugins>
  </build>
  </profile>
+
+ <profile>
+ <id>jdk-toolchain</id>
+ <activation>
+ <property>
+ <name>jdk.version</name>
+ </property>
+ </activation>
+ <build>
+ <plugins>
+ <!-- See http:https://maven.apache.org/guides/mini/guide-using-toolchains.html -->
+ <plugin>
+ <groupId>org.apache.maven.plugins</groupId>
+ <artifactId>maven-toolchains-plugin</artifactId>
+ <executions>
+ <execution>
+ <phase>validate</phase>
+ <goals>
+ <goal>toolchain</goal>
+ </goals>
+ </execution>
+ </executions>
+ <configuration>
+ <toolchains>
+ <jdk>
+ <version>${jdk.version}</version>
+ </jdk>
+ </toolchains>
+ </configuration>
+ </plugin>
+ </plugins>
+ </build>
+ </profile>
  </profiles>
 
 </project>