Merges custom fields into the lead. Set a field value to null to
delete that field.
Requires leads:import permission.
API key prefixed with nl_live_ or nl_test_
Account-scoped sequential lead ID
Updated lead
Sequential, account-scoped identifier
Unique per account
new, contacted, qualified, disqualified ObjectId reference to AgentConfig
ObjectId reference to AbTest
manual, ab_test, auto Key-value string map of custom fields