Merge pull request #137 from Omega-R/feature/hotfix

Sticky header call getStickyId with id = -1 bug fixed

Author: anton-knyazev

omegarecyclerviewlibs/src/main/java/com/omega_r/libs/omegarecyclerview/sticky_decoration/StickyDecoration.java

@@ -49,7 +49,7 @@ private long calculateStickerIdAndDrawIt(Canvas canvas, RecyclerView parent, boo
                     View stickerView = stickyHolder.itemView;
                     int top = getStickerTop(isReverseLayout, childView, stickerView, layoutPos + 1);
 
-                    long previousStickyId = mStickyAdapter.getStickyId(adapterPosition - 1);
+                    long previousStickyId = adapterPosition == 0 ? currentStickerId : mStickyAdapter.getStickyId(adapterPosition - 1);
 
                     if (layoutPos == 0 && top > 0 && adapterPosition > 0
                             && hasSticker(adapterPosition - 1)