When creating an intrabank contact, you can pass either the accountId or accountNumber to link the account.
Note that contacts have the three possible types in the Contact Object: others, selfAch, and selfIntrabank.
If the user is linking intrabank accounts owned by the same entity, this is referred to as a selfIntrabank contact.
In this situation, they should create a separate contact for the selfIntrabank link using only the intrabank sub-object.
If users try to include a self-owned intrabank account when creating a standard others contact, they receive an error such as "EC_CONTACT_INVALID_SELF_INTRABANK_REQUEST" and "Invalid self intrabank request". They should remove the intrabank sub-object and create a separate contact for the selfIntrabank link.
