src/main/java/com/simpligility/maven/plugins/android/phase09package/ApkMojo.java
private void collectFiles( File folder, final List<File> collectedFiles )
    {
        folder.listFiles( new FileFilter()
        {
            @Override
            public boolean accept( File file )
            {
                if ( file.isDirectory() )
                {
                    collectFiles( file, collectedFiles );
                }
                else if ( file.isFile() )
                {
                    if ( !file.getName().endsWith( ".class" ) )
                    {
                        collectedFiles.add( file );
                    }
                }
                return false;
            }
        } );

    }
private void collectFiles( File folder, final List<File> collectedFiles )
    {
        folder.listFiles( new FileFilter()
        {
            @Override
            public boolean accept( File file )
            {
                if ( file.isDirectory() )
                {
                    collectFiles( file, collectedFiles );
                }
                else if ( file.isFile() )
                {
                    if ( !file.getName().endsWith( ".class" ) )
                    {
                        collectedFiles.add( file );
                    }
                }
                return false;
            }
        } );

    }
Collect all Files from Folder (recursively) that are not class files.