WuSiYu/papermc-1.17.1-unfix-sand-duplication

This fork "un-fix" sand(and other gravity block) duplication in lastest(1.17.1, Sep 2021) papermc server, sand dup machine works now! --- 该fork反向修复了末地传送门的刷沙bug，刷沙机又可以正常使用了

JavaNOASSERTION