11 U.S.C. § 542(b). On facts presented, insurance coverage dispute found not to be a core proceeding and not a proper § 542(b) turnover action. Although mandatory abstention did not apply because there was diversity jurisdiction, court exercised discretion to abstain under 28 U.S.C. § 1334(c)(1) in favor of pending arbitration proceeding where no overriding, countervailing bankruptcy purpose.