private int compareDegrees(final OutboundMobilityCandidacyContest o) { return executionDegreesCompareHash( o.getOutboundMobilityCandidacyContestGroup().getExecutionDegreeSet()) .compareTo( executionDegreesCompareHash( getOutboundMobilityCandidacyContestGroup().getExecutionDegreeSet())); }