Revert to checkstyle 6.x for Java 7 support
Revert to checkstyle 6.x for Java 7 support

zxing/zxing,daverix/zxing,l-dobrev/zxing,zxing/zxing,shixingxing/zxing,daverix/zxing,daverix/zxing,tanelihuuskonen/zxing,tanelihuuskonen/zxing,daverix/zxing,daverix/zxing,shixingxing/zxing,l-dobrev/zxing