code: public void execute()
          throws MojoExecutionException, MojoFailureException
      {
          if ( isSkipping() )
          {
              getLog().debug( "Skipping execution, as demanded by user." );
              return;
          }
          if ( transformationSets == null || transformationSets.length == 0 )
          {
              throw new MojoFailureException( "No TransformationSets configured." );
          }
          checkCatalogHandling();
  
          Object oldProxySettings = activateProxy();
          try
          {
              Resolver resolver = getResolver();
              for ( int i = 0; i < transformationSets.length; i++ )
              {
                  TransformationSet transformationSet = transformationSets[i];
                  resolver.setXincludeAware( transformationSet.isXincludeAware() );
                  resolver.setValidating( transformationSet.isValidating() );
                  transform( resolver, transformationSet );
              }
          }
          finally
          {
              passivateProxy( oldProxySettings );
          }
      }
docs: Called by Maven to run the plugin.