diff --git a/maven-core/src/test/java/org/apache/maven/project/ProjectBuilderTest.java b/maven-core/src/test/java/org/apache/maven/project/ProjectBuilderTest.java
index 4833b00351..644f6d1eb8 100644
--- a/maven-core/src/test/java/org/apache/maven/project/ProjectBuilderTest.java
+++ b/maven-core/src/test/java/org/apache/maven/project/ProjectBuilderTest.java
@@ -34,6 +34,7 @@ import java.util.Properties;
 import org.apache.maven.AbstractCoreMavenComponentTestCase;
 import org.apache.maven.artifact.InvalidArtifactRTException;
 import org.apache.maven.execution.MavenSession;
+import org.apache.maven.model.Plugin;
 import org.apache.maven.model.building.FileModelSource;
 import org.apache.maven.model.building.ModelBuildingRequest;
 import org.apache.maven.model.building.ModelSource;
@@ -328,4 +329,17 @@ public class ProjectBuilderTest
         assertEquals( 1, project.getMailingLists().size() );
         assertEquals( 1, project.getResources().size() );
     }
+
+    public void testPropertyInPluginManagementGroupId()
+            throws Exception
+    {
+        File pom = getProject( "MNG-6983" );
+
+        MavenSession session = createMavenSession( pom );
+        MavenProject project = session.getCurrentProject();
+
+        for (Plugin buildPlugin : project.getBuildPlugins()) {
+            assertNotNull( "Missing version for build plugin " + buildPlugin.getKey(), buildPlugin.getVersion() );
+        }
+    }
 }
diff --git a/maven-core/src/test/projects/project-builder/MNG-6983/parent-pom.xml b/maven-core/src/test/projects/project-builder/MNG-6983/parent-pom.xml
new file mode 100644
index 0000000000..3aed9678e5
--- /dev/null
+++ b/maven-core/src/test/projects/project-builder/MNG-6983/parent-pom.xml
@@ -0,0 +1,38 @@
+<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>org.example</groupId>
+    <artifactId>parent</artifactId>
+    <version>0.0.1-SNAPSHOT</version>
+    <packaging>pom</packaging>
+
+    <properties>
+        <codehaus.groupId>org.codehaus.mojo</codehaus.groupId>
+    </properties>
+
+    <build>
+        <pluginManagement>
+            <plugins>
+                <plugin>
+                    <groupId>${codehaus.groupId}</groupId>
+                    <artifactId>build-helper-maven-plugin</artifactId>
+                    <version>3.2.0</version>
+                    <executions>
+                        <execution>
+                            <id>add-source-config</id>
+                            <phase>generate-sources</phase>
+                            <goals>
+                                <goal>add-source</goal>
+                            </goals>
+                            <configuration>
+                                <sources>
+                                    <source>.</source>
+                                </sources>
+                            </configuration>
+                        </execution>
+                    </executions>
+                </plugin>
+            </plugins>
+        </pluginManagement>
+    </build>
+</project>
diff --git a/maven-core/src/test/projects/project-builder/MNG-6983/pom.xml b/maven-core/src/test/projects/project-builder/MNG-6983/pom.xml
new file mode 100644
index 0000000000..648f7fc9e9
--- /dev/null
+++ b/maven-core/src/test/projects/project-builder/MNG-6983/pom.xml
@@ -0,0 +1,22 @@
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+
+    <parent>
+        <groupId>org.example</groupId>
+        <artifactId>parent</artifactId>
+        <version>0.0.1-SNAPSHOT</version>
+        <relativePath>./parent-pom.xml</relativePath>
+    </parent>
+
+    <artifactId>child</artifactId>
+    <packaging>jar</packaging>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>${codehaus.groupId}</groupId>
+                <artifactId>build-helper-maven-plugin</artifactId>
+            </plugin>
+        </plugins>
+    </build>
+</project>
diff --git a/maven-model/src/main/mdo/maven.mdo b/maven-model/src/main/mdo/maven.mdo
index 1f1f9d1864..7f439faa9f 100644
--- a/maven-model/src/main/mdo/maven.mdo
+++ b/maven-model/src/main/mdo/maven.mdo
@@ -2314,18 +2314,12 @@
         return id.toString();
     }
 
-    //TODO we shall reset key variable when groupId/artifactId change
-    private String key = null;
     /**
      * @return the key of the plugin, ie <code>groupId:artifactId</code>
      */
     public String getKey()
     {
-        if ( key == null )
-        {
-            key = constructKey( groupId, artifactId );
-        }
-        return key;
+        return constructKey( groupId, artifactId );
     }
 
     /**