private static void checkXYSign(int x, int y) {
    Preconditions.checkArgument(x >= 0, "x must be >= 0");
    Preconditions.checkArgument(y >= 0, "y must be >= 0");
  }
Common code for checking that x and y are >= 0

@param x x coordinate to ensure is >= 0
@param y y coordinate to ensure is >= 0
imagepipeline-base/src/main/java/com/facebook/imagepipeline/bitmaps/PlatformBitmapFactory.java