I have a code which was working fine with Spring boot 2 but when i moved it to spring 3, I get an error message saying

java.lang.IllegalArgumentException: Cannot deserialize value of type `java.time.Instant` from Object value (token `JsonToken.START_OBJECT`) at [Source: UNKNOWN; byte offset: #UNKNOWN] (through reference chain: java.util.ArrayList[0]->com.oxane.argon.kpi.KpiFieldDTO["lastModifiedDate"])

I have a query which was quite complex and uses many joins and CTE after that I fetch limited data from a POJO table. So I use NamedParameterJdbcTemplate to fetch list of result after that I convert List<Map<String,Object>> to my DTO using object mapper, which was working fine before spring 2 now I receive the above error. Data for Instant field is stored as Datetimeoffset in DB because I haven’t added any line for backward compatibility.

My DTO looks like this

public class dDTO {

private String loanId;

private String obligor;

private LocalDate fsDateLatest;

private LocalDate lastUpdate;

private Instant createdDate;

private Instant lastModifiedDate;

private Integer investmentType;

private LocalDate maturityDate;

private String reportingCurrency;

private BigDecimal debtWeightedSpread1L;

private Integer lastModifiedBy;

private String lastModifiedByEmail;
//getters and setters and constructors
}

Code to convert data

List<Map<String, Object>> kpiByObligorAndFs;
final List<DTO> findAllByObligorAndFsDateLessThanEqual = objectMapper.convertValue(kpiByObligorAndFs, new TypeReference<List<DTO>>() {
    });