@Override
    public boolean equals(Object o) {
        if (this == o) {
            return true;
        }
        if (o == null || getClass() != o.getClass()) {
            return false;
        }
        JsonRowDataSerializationSchema that = (JsonRowDataSerializationSchema) o;
        return rowType.equals(that.rowType)
                && timestampFormat.equals(that.timestampFormat)
                && mapNullKeyMode.equals(that.mapNullKeyMode)
                && mapNullKeyLiteral.equals(that.mapNullKeyLiteral);
    }
The string literal when handling mode for map null key LITERAL.
inlong-sort/sort-formats/format-rowdata/format-rowdata-json/src/main/java/org/apache/inlong/sort/formats/json/JsonRowDataSerializationSchema.java