build_children

# File activerecord/lib/active_record/associations/preloader/branch.rb, line 120
          def build_children(children)
            Array.wrap(children).flat_map { |association|
              Array(association).flat_map { |parent, child|
                Branch.new(
                  parent: self,
                  association: parent,
                  children: child,
                  associate_by_default: associate_by_default,
                  scope: scope
                )
              }
            }
          end