HAVANA (AP) — Cuba is holding a rare referendum on an unusually contentious law — a government-backed code that would allow same-sex couples to marry and adopt. It also outlines the rights of children and grandparents and tries to protect against gender violence. The code of more than 400 articles has been questioned by many members of the island’s increasingly vocal evangelical community. President Miguel Díaz-Canel has promoted the law but acknowledged Sunday that “it still has issues that our society as a whole does not understand,.”