An intricate set of contractual, bureaucratic and statutory mechanisms governs billing calculations for workers’ compensation insurance. In a case where a property management company alleged it overpaid for coverage because its maintenance employees were misclassified as construction workers — and an insurer counterclaimed — U.S. District Judge Sue E. Myerscough provided a nice review of how this complex scheme works. JSM Management, an apartment manager in Champaign, sued several of its workers’ compensation insurers for …