title: AEM 6.1 extend ThumbnailProcess Workflow Step
body: <p>I'm trying to extend the <strong><em>com.day.cq.dam.core.process.ThumbnailProcess</em></strong> class.</p>
  
  <p>I'm using Java JDK 1.8.0_65, Maven 3.0.5 and Adobe AEM 6.1</p>
  
  <p>When I compile my code I get this error:</p>
  
  <blockquote>
    <p>[ERROR] Failed to execute goal
    org.apache.felix:maven-scr-plugin:1.20.0:scr (generate-scr-descriptor)
    on project my.pack.common.PROCESS: Execution
    generate-scr-descriptor of goal
    org.apache.felix:maven-scr-plugin:1.20.0:scr failed: An API
    incompatibility was encountered while executing
    org.apache.felix:maven-scr-plugin:1.20.0:scr: java.lang.VerifyError:
    (class: com/day/cq/dam/core/process/ThumbnailProcess, method: 
    signature: ()V) Constructor must call super()or this()</p>
    
    <p>[ERROR] ----------------------------------------------------- </p>
    
    <p>[ERROR] realm =    plugin>org.apache.felix:maven-scr-plugin:1.20.0 [ERROR] strategy =
    org.codehaus.plexus.classworlds.strategy.SelfFirstStrategy </p>
    
    <p>[ERROR]
    urls[0] =
    file:/C:/Users/Dwecol/.m2/repository/org/apache/felix/maven-scr-plugin/1.20.0/maven-scr-plugin-1.20.0.jar</p>
    
    <p>[ERROR] urls[1] =
    file:/C:/Users/Dwecol/.m2/repository/org/apache/maven/maven-archiver/2.2/maven-archiver-2.2.jar
    [ERROR] urls[2] =
    file:/C:/Users/Dwecol/.m2/repository/junit/junit/3.8.1/junit-3.8.1.jar
    [ERROR] urls[3] =
    file:/C:/Users/Dwecol/.m2/repository/org/codehaus/plexus/plexus-archiver/1.0-alpha-7/plexus-archiver-1.0-alpha-7.jar
    [ERROR] urls[4] =
    file:/C:/Users/Dwecol/.m2/repository/org/apache/felix/org.apache.felix.scr.generator/1.12.0/org.apache.felix.scr.generator-1.12.0.jar</p>
    
    <p>[ERROR] urls[5] =
    file:/C:/Users/Dwecol/.m2/repository/org/ow2/asm/asm-all/5.0.2/asm-all-5.0.2.jar
    [ERROR] urls[6] =
    file:/C:/Users/Dwecol/.m2/repository/org/osgi/org.osgi.core/4.2.0/org.osgi.core-4.2.0.jar</p>
    
    <p>[ERROR] urls[7] =
    file:/C:/Users/Dwecol/.m2/repository/org/osgi/org.osgi.compendium/4.2.0/org.osgi.compendium-4.2.0.jar</p>
    
    <p>[ERROR] urls[8] =
    file:/C:/Users/Dwecol/.m2/repository/org/sonatype/plexus/plexus-build-api/0.0.7/plexus-build-api-0.0.7.jar</p>
    
    <p>[ERROR] urls[9] =
    file:/C:/Users/Dwecol/.m2/repository/org/codehaus/plexus/plexus-utils/1.5.8/plexus-utils-1.5.8.jar
    [ERROR] Number of foreign imports: 1 [ERROR] import: Entry[import 
    from realm
    ClassRealm[project>mypro:my.pack.edidomus.common.PROCESS:1.0.1-SNAPSHOT,
    parent: ClassRealm[maven.api, parent: null]]] 
    [ERROR] -> [Help 1] 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] For more information about
    the errors and possible solutions, please read the following articles:
    [ERROR] [Help 1]
    <a href="http://cwiki.apache.org/confluence/display/MAVEN/PluginContainerException" rel="nofollow">http://cwiki.apache.org/confluence/display/MAVEN/PluginContainerException</a></p>
  </blockquote>
  
  <p>My class is somenthing like this:</p>
  
  <pre><code>@Component
  @Service
  @Properties({
  @Property(name = Constants.SERVICE_DESCRIPTION, value ="MyThumbnailProcess"),
  @Property(name = Constants.SERVICE_VENDOR, value = "Me"),
  @Property(name = "process.label", value = "My Thumbnail Proc2")}
  public class MyThumbnailProc extends ThumbnailProcess {
  public MyThumbnailProc(){super();}
  @Override
  public void execute(WorkItem workItem, WorkflowSession workflowSession, MetaDataMap metaData) throws WorkflowException {
  //do stuff -&gt; create newMetaDataMap 
  super.execute(workItem, workflowSession, newMetaDataMap);
  }
  </code></pre>
  
  <p>Do you have any suggest?</p>