取引開始 カスタマイズの場合 Database.LeadConvert

https://developer.salesforce.com/docs/atlas.ja-jp.apexcode.meta/apexcode/apex_dml_convertLead.htm

Lead myLead = new Lead(LastName = ‘Fry’, Company=’Fry And Sons’);
insert myLead;

Database.LeadConvert lc = new Database.LeadConvert();
lc.setLeadId(myLead.id);

LeadStatus convertStatus = [SELECT Id, MasterLabel FROM LeadStatus WHERE IsConverted=true LIMIT 1];
lc.setConvertedStatus(convertStatus.MasterLabel);

Database.LeadConvertResult lcr = Database.convertLead(lc);
System.assert(lcr.isSuccess());