Hibernate UserType: invalid LocalDate stored in database

Question

I am unable to store date (LocalDate) properly in Postgres database using Hibernate (5.3.7) UserType. It intermittently fails to store correct dob. Most of the dates (dob) has invalid day of month value like "dob": "1986-12-363".

The database store call is made inside CompletableFuture.runAsync( () -> {... store in database ..});

I am unable to trace the issue. It fails intermittently that makes it more confusing. I am not sure what is wrong here. I will really appreciate any help to fix the issue.

I have followed this tutorial.

@Entity
@Table(name = "abc")
@TypeDef(name = "userJsonType", typeClass = UserJsonType.class)
public class ABC implements Serializable {
    ....
    @Type(type = "userJsonType")
    private final List<User> users;
    ....
}

public class User implements Serializable{
....
    @JsonFormat(shape = JsonFormat.Shape.STRING, pattern = "yyyy-MM-dd")
    private final LocalDate dob;
....
}

public class UserJsonType implements UserType {
    @Override
    public int[] sqlTypes() {
        return new int[]{Types.JAVA_OBJECT};
    }

    @Override
    public Class returnedClass() {
        return new TypeReference<List<User>>() {
        }.getClass();
    }

    @Override
    public boolean equals(Object x, Object y) throws HibernateException {
        return false;
    }

    @Override
    public int hashCode(Object x) throws HibernateException {
        if (null == x) {
            return 0;
        }
        return x.hashCode();
    }

    @Override
    public Object nullSafeGet(ResultSet rs, String[] names, SharedSessionContractImplementor session, Object owner) throws HibernateException, SQLException {
        final String cellContent = rs.getString(names[0]);
        if (cellContent == null) {
            return null;
        }
        try {
            final ObjectMapper mapper = new ObjectMapper();
            mapper.registerModule(new JavaTimeModule());
            return mapper.readValue(cellContent.getBytes("UTF-8"), returnedClass());
        } catch (final Exception ex) {
            throw new RuntimeException("Failed to convert String to CustomerDetails: " + ex.getMessage(), ex);
        }
    }

    @Override
    public void nullSafeSet(PreparedStatement ps, Object value, int index, SharedSessionContractImplementor session) throws HibernateException, SQLException {
        if (value == null) {
            ps.setNull(index, Types.OTHER);
            return;
        }
        try {
            final ObjectMapper mapper = new ObjectMapper();
            mapper.registerModule(new JavaTimeModule());
            final StringWriter w = new StringWriter();
            mapper.writeValue(w, value);
            w.flush();
            ps.setObject(index, w.toString(), Types.OTHER);
        } catch (final Exception ex) {
            throw new RuntimeException("Failed to convert CustomerDetails to String: " + ex.getMessage(), ex);
        }
    }

    @Override
    public Object deepCopy(Object value) throws HibernateException {
        try {
            // use serialization to create a deep copy
            ByteArrayOutputStream bos = new ByteArrayOutputStream();
            ObjectOutputStream oos = new ObjectOutputStream(bos);
            oos.writeObject(value);
            oos.flush();
            oos.close();
            bos.close();

            ByteArrayInputStream bais = new ByteArrayInputStream(bos.toByteArray());
            return new ObjectInputStream(bais).readObject();
        } catch (ClassNotFoundException | IOException ex) {
            throw new HibernateException(ex);
        }
    }

    @Override
    public boolean isMutable() {
        return false;
    }

    @Override
    public Serializable disassemble(Object value) throws HibernateException {
        Object copy = deepCopy(value);

        if (copy instanceof Serializable) {
            return (Serializable) copy;
        }

        throw new SerializationException(String.format("Cannot serialize '%s', %s is not Serializable.", value, value.getClass()), null);
    }

    @Override
    public Object assemble(Serializable cached, Object owner) throws HibernateException {
        return deepCopy(cached);
    }

    @Override
    public Object replace(Object original, Object target, Object owner) throws HibernateException {
        return deepCopy(original);
    }
}