adjustments made to calculate free cashflows to the firm

as we know that to get from accounting earnings to cashflows to the firm , we will have to add back all non cash charges such as depreciation, subtract out all cash outflows that represent capital expenditure and finally net out changes in noncash working capital.
but here in this problem, we observe that the operating income is adjusted by adding back the non recurring expenses {restructuring charges} and adjusting income for the conversion of operating lease commitments to debt, how and why did we do that ? it has completely went over my head.
here's the actual note:-

a. Operating income The firm reported an operating income of $201.25 million on revenues of $4.30 billion for the year. Adding back nonrecurring expenses (restructuring charge of $83.2 million in 2013) and adjusting income for the conversion of operating lease commitments to debt, we estimated an adjusted operating income of $313.19 million. The present value of lease commitments over the next seven years, discounted back at Harman’s pretax cost of debt of 4.75% is $143.95 million. We added back the operating lease expense from 2013 ($49.3 million) and subtracted out an estimated depreciation of $20.6 million to arrive at adjusted operating income. Adjusted operating income = 201.25 + 83.2 + (49.3 − 20.6) = $313.2