public void onEnterRepeatingGroup(
            final Token token,
            final List<Token> groupFields,
            final List<Token> groupGroups,
            final List<Token> groupVarData)
        {
            groupPathsByField.put(token, currentGroupPath());
            groupPath.addLast(token);
            walkSchemaLevel(this, groupFields, groupGroups, groupVarData);
            groupPath.removeLast();
        }
Encodes the state machine as a graphviz dot diagram.
@param sb the string builder to append to.
@param indent the indentation to use.
sbe-tool/src/main/java/uk/co/real_logic/sbe/generation/common/FieldPrecedenceModel.java