how to join pjf_projects_all_b and PAY_COST_ALLOCATION_KEYFLEX in fusion

In EBS we used the below query and later it needs to be linked with AP Invoices details….

SELECT
hou.name,
pcak.segment2 cost_center,

from
pjf_projects_all_b ppa,
hr_all_organization_units hou,
PAY_COST_ALLOC_KEYFLEX pcak
where
1=1
AND ppa.carrying_out_organization_id = hou.organization_id (+)
AND pcak.cost_allocation_keyflex_id (+)= hou.cost_allocation_keyflex_id

But in Fusion cost_allocation_keyflex_id is NULL in hr_all_organization_units