I finally found a solution. Here it is if someone needs it :
private void buildDateMapping(String fieldName, String attributeName, TemporalType tt, JPADynamicTypeBuilder builder){
DirectToFieldMapping mapping = new DirectToFieldMapping();
mapping.setAttributeName(attributeName);
mapping.setFieldName(fieldName);
Class<?> fieldClassification;
if (tt.equals(TemporalType.DATE)) {
fieldClassification = java.sql.Date.class;
} else if(tt.equals(TemporalType.TIME)) {
fieldClassification = java.sql.Time.class;
} else {
// TIMESTAMP
fieldClassification = java.sql.Timestamp.class;
}
mapping.setFieldClassification(fieldClassification);
mapping.setConverter(new TypeConversionConverter(mapping));
builder.addMapping(mapping);
}