private String getFilterPrimaryKey(Node node) {
        if (node instanceof MongoExtractNode) {
            if (null != node.getProperties().get(SOURCE_MULTIPLE_ENABLE_KEY)
                    && node.getProperties().get(SOURCE_MULTIPLE_ENABLE_KEY).equals("true")) {
                return node.getPrimaryKey();
            }
        }
        return null;
    }
Get filter PrimaryKey for Mongo when multi-sink mode
inlong-sort/sort-core/src/main/java/org/apache/inlong/sort/parser/impl/FlinkSqlParser.java