@Override
        public Optional<MemberShape> getMember(String memberName) {
            if ("member".equals(memberName)) {
                return Optional.ofNullable(member);
            } else {
                return Optional.empty();
            }
        }
Builder used to create a List or Set shape.
@param <B> Concrete builder type.
@param <S> Shape type being created.
smithy-model/src/main/java/software/amazon/smithy/model/shapes/CollectionShape.java