code: private void prepareExtensions()
              throws MojoExecutionException
      {
          List<String> includes = new ArrayList<>();
          for ( JnlpExtension extension : jnlpExtensions )
          {
              // Check extensions (mandatory name, title and vendor and at least one include)
  
              checkExtension( extension );
  
              for ( String o : extension.getIncludes() )
              {
                  includes.add( o.trim() );
              }
  
              if ( StringUtils.isEmpty( extension.getOutputFile() ) )
              {
                  String name = extension.getName() + ".jnlp";
                  verboseLog(
                          "Jnlp extension output file name not specified. Using default output file name: " + name + "." );
                  extension.setOutputFile( name );
              }
          }
          // copy all includes libs fro extensions to be exclude from the mojo
          // treatments (extensions by nature are already signed)
          if ( dependencies == null )
          {
              dependencies = new Dependencies();
          }
  
          if ( dependencies.getExcludes() == null )
          {
              dependencies.setExcludes( new ArrayList<String>() );
          }
  
          dependencies.getExcludes().addAll( includes );
      }
docs: Prepare extensions.
  <p>
  Copy all includes of all extensions as to be excluded.
  
  @throws MojoExecutionException if could not prepare extensions