PORTLAND — A complaint alleging that a ballot initiative agreement negotiated by Oregon Gov. Kate Brown, Nike and a public employees union was illegal was authored by an attorney affiliated with political opponents of both Brown and unions. Attorney Jill Gibson acknowledged Friday that she had drafted the complaint filed last month with the Oregon Secretary of State’s office by a Portland man named Richard Leonetti, Oregon Public Broadcasting reported Monday. The complaint challenged the deal to keep an initiative off the ballot that the Democratic governor helped broker in early July. The union-backed initiative would have required Nike and other large companies to disclose tax payments and other business details.