public CodecInteraction determineGroupIsEmpty(final Token token)
            {
                return determineGroupIsEmptyInteractions.computeIfAbsent(
                    token, (t) -> new DetermineGroupIsEmpty(groupPathsByField.get(t), t));
            }
Find or create a {@link CodecInteraction} to represent determining a
repeating group is empty.

<p>For encoding, this will be when the group count is supplied, e.g.,
{@code encoder.myGroupCount(0)}.

<p>For decoding, this will be when the group is read, e.g.,
{@code decoder.myGroup()}.

<p>The supplied token must carry a {@link Signal#BEGIN_GROUP} signal.

@param token the token identifying the group
@return the {@link CodecInteraction} instance
sbe-tool/src/main/java/uk/co/real_logic/sbe/generation/common/FieldPrecedenceModel.java