Third-party respondents in state court supplementary proceedings usually can’t use diversity jurisdiction to yank a judgment creditor’s “citation to discover assets” into federal court. But Travelers Commercial Insurance Co. invoked an exception to this general rule when Maria and Jose Jimenez tried to force it to pay a $600,000 Cook County judgment against Stephen Kiefer.Kiefer had $100,000 in auto insurance from Travelers when he allegedly caused an accident that injured Maria. The company paid …