using java 1.7 for compilation (for ClassLoader.close() called in DefaultPluginManager)

pom.xml

@@ -1,6 +1,6 @@
 <?xml version="1.0"?>
 <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">
-    
+
     <parent>
         <groupId>org.sonatype.oss</groupId>
         <artifactId>oss-parent</artifactId>
@@ -29,10 +29,11 @@
         <url>git@github.com/decebals/pf4j.git</url>
       <tag>HEAD</tag>
   </scm>
-        
+
     <properties>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
-    </properties>   
+        <java.version>1.7</java.version>
+    </properties>
 
     <build>
         <plugins>
@@ -41,12 +42,12 @@
                 <artifactId>maven-compiler-plugin</artifactId>
                 <version>2.3.2</version>
                 <configuration>
-                    <source>1.6</source>
+                    <source>${java.version}</source>
-                    <target>1.6</target>
+                    <target>${java.version}</target>
                     <optimize>true</optimize>
                 </configuration>
             </plugin>
-            
+
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-javadoc-plugin</artifactId>
@@ -83,12 +84,12 @@
                     <tagNameFormat>release-@{project.version}</tagNameFormat>
                 </configuration>
             </plugin>
-            
+
             <plugin>
                 <artifactId>maven-resources-plugin</artifactId>
                 <version>2.4.3</version>
             </plugin>
-            
+
             <plugin>
                 <artifactId>maven-jar-plugin</artifactId>
                 <version>2.4</version>