@Override
    public int hashCode() {
        return Objects.hash(rowType, timestampFormat, mapNullKeyMode, 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