public CodecInteraction accessField(final Token token)
            {
                return accessFieldInteractions.computeIfAbsent(
                    token, (t) -> new AccessField(groupPathsByField.get(t), t, topLevelBlockFields.contains(t)));
            }
Find or create a {@link CodecInteraction} to represent accessing the field identified
by the given token.

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

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