private static List<FieldRelation> createJoinerFieldRelations(List<StreamField> fieldList,
            Map<String, StreamField> constantFieldMap) {
        return fieldList.stream()
                .map(streamField -> {
                    FormatInfo formatInfo = FieldInfoUtils.convertFieldFormat(
                            streamField.getFieldType(), streamField.getFieldFormat());
                    FunctionParam inputField;
                    String fieldKey = String.format("%s-%s", streamField.getOriginNodeName(),
                            streamField.getOriginFieldName());
                    StreamField constantField = constantFieldMap.get(fieldKey);
                    if (constantField != null) {
                        if (formatInfo != null && formatInfo.getTypeInfo() == StringTypeInfo.INSTANCE) {
                            inputField = new StringConstantParam(constantField.getFieldValue());
                        } else {
                            inputField = new ConstantParam(constantField.getFieldValue());
                        }
                    } else {
                        inputField = new FieldInfo(streamField.getOriginFieldName(),
                                streamField.getOriginNodeName(), formatInfo);
                    }
                    FieldInfo outputField = new FieldInfo(streamField.getFieldName(), formatInfo);
                    return new FieldRelation(inputField, outputField);
                }).collect(Collectors.toList());
    }
Create relation of fields in join function.
inlong-manager/manager-pojo/src/main/java/org/apache/inlong/manager/pojo/sort/util/FieldRelationUtils.java