Oracle DB queries through JPA/Hibernate from java.util.Date - spring

Question

I am currently working on a migration of a Spring Boot application from MariaDB to OracleDB. The Spring/Java backend uses Hibernate/JPA to generate queries for the MariaDB database, and as such in theory the migration should be fairly painless. Change a dialect and you're done. In practice, it turns out that the hibernate dialect for OracleDB 12C makes some odd assumptions when it comes to binding types to database types. The backend still uses the old java.util.Date type for all of its dates, which Hibernate seems to want desperately to cast to either a Long (even more outdated as far as I could find) or a BLOB type of some sort. BLOBs are great of course, but it seems much more intuitive to map a Date to a DATE.
Because the row is currently set to expect a DATE, I get the following error whenever I try to access the row:
InvalidDataAccessResourceUsageException: could not extract ResultSet
ORA-00932: inconsistent datatypes: expected - got BLOB
I have tried using the JPA Converter feature to manually cast these Date objects to something Hibernate wouldn't mess up, but this resulted in Hibernate expecting a VARBINARY as this article describes:
https://dzone.com/articles/leaky-abstractions-or-how-bind
#Converter(autoApply = false)
public class DateDATEAttributeConverter implements AttributeConverter<Date, DATE> {
#Override
public DATE convertToDatabaseColumn(Date date){
return new DATE(); // conversion to be done later
}
#Override
public Date convertToEntityAttribute(DATE date) {
return new Date(); // conversion to be done later
}
}
Using this very minimal converter, and running through the code step-by-step with a debugger, shows that everything seems to be properly attached to the preparedstatement, but is then refused by Hibernate with an
org.hibernate.exception.SQLGrammarException: could not extract ResultSet
error.
Afterwards I decided to try making a customer UserType like in the above article, and described in further detail here:
https://www.baeldung.com/hibernate-custom-types
I currently cast the java.util.Date to an Oracle DATE through the use of this custom type. The #Type annotation is used to make sure the relevant field is converted using this CustomType implementation. Sadly, after implementing all this, the same error as before returns. It seems somewhere beneath the hood there is still a conversion/binding going on that I haven't managed to influence.
#Override
public Object nullSafeGet(
ResultSet rs,
String[] names,
SessionImplementor session,
Object owner
)
throws SQLException {
LOGGER.debug("nullSafeGet: " + names[0]);
return rs.getTimestamp(names[0]);
}
#Override
public void nullSafeSet(
PreparedStatement st,
Object value,
int index,
SessionImplementor session
)
throws SQLException {
if(Objects.isNull(value)){
st.setNull(index, Types.DATE);
}else{
Date dateUtil = (Date)value;
LocalDate localDate = dateUtil.toInstant().atZone(ZoneId.systemDefault()).toLocalDate();
java.sql.Date dateSQL = java.sql.Date.valueOf(localDate);
DATE date = new DATE(dateSQL);
LOGGER.debug("nullSafeSet: " + date);
st.setObject(index, date);
}
}
Is there any established method to get around this? I have searched around online for quite a bit, but I didn't get much further than these two articles, or being told to stop using old types such as Date. Sadly with big old projects and new deadlines that is not a preferable option.