Creating a Business Data Model that has a list of another BDM as an attribute, and setting this relationship as an aggregation does not allow for complete contract creation for the child BDM. The wizard for contract creation displays an accordion, that when opened, should display a list of all the child BDM's attributes. However, a bug occurs where the arrow used for opening the accordion flashes and disappears, and the list of attributes is not displayed. This means that the only child BDM attribute entered to the contract is the persistence ID.
macOS Mojave, 10.14.6 (18G3020), MacBook Pro (13-inch, 2017, Two Thunderbolt 3 ports)
The only workaround for now is to use composition for every relationship, but this presents other complications when trying to create other BDM structures.