求懂印尼民俗的鉴定下 — Lawang Sewu basement, is the 'blood everywhere' story real history or repost rot

Picked this up off a SE Asia travel board and can't tell what's history vs what got added later, hoping someone here actually knows. Lawang Sewu in Semarang, 'thousand doors', gorgeous Dutch railway HQ, A building done 1907 rest by 1919. The dark bit: Japanese took it in 1942 and turned the building……