Support native query without parameters

[stIncMale]

HIBERNATE-60

[stIncMale]

MqlType was made package-access. Furthermore, ObjectIdJdbcType.MQL_TYPE explicitly points to our implementation of the JdbcType for ObjectId, which improves readability.

[stIncMale]

This PR only needed this new method. However, I also wanted to stop using Object.class to represent "unknown domain type", which caused the rest of the changes.

[stIncMale]

I tried also using SqlResultSetMapping.classes, but I don't think Hibernate ORM implements that one correctly: instead of trying to find the corresponding constructor, it uses the no-argument constructor and then tries to populate the object, searching for the field/property based on the ColumnResult.name, which represents the column name, and does not have to match the name of a field/property.

[vbabanin]

[nit/optional]

Suggested change

	if (fieldName.equals(ID_FIELD_NAME)) {
	excludeId = true;
	}
	excludeId |= ID_FIELD_NAME.equals(fieldName);

[stIncMale]

Done in 942a177.

[vbabanin]

As I see, Hibernate supports DTO mapping both via Tuple and directly to an instance of DTO class with the help of @ConstructorResult. I suggest adding tests for latter approach as well to have wider use-case coverage.

To keep things simple, we could add @ConstructorResult to existing entities used in these tests (e.g., BasicCrudIntegrationTests.Item, etc.) rather than introducing new DTO-only classes (it works in both cases). Then we could extend the Dto nested test class with constructor-based variants (e.g., testBasicValues that uses constructor mapping):

() -> assertEq(
    item,
    session.createNativeQuery(mql, Item.CONSTRUCTOR_MAPPING_FOR_ITEM, Item.class)
           .getSingleResult());

Findings so far: constructor mapping works with entities that have only basic types, embeddables, or structs. It fails with Collection or subtypes - Hibernate ORM throws a NullPointerException because CollectionJavaType returns a null as recommended type. If array is used in @ColumnResult for a parameter that is Collection, the parametrized constructor is not invoked and Hibernate falls back to using the default constructor and field mapping.

@Override
	public JdbcType getRecommendedJdbcType(JdbcTypeIndicators context) {
		// none
		return null;
	}

That looks like a Hibernate bug (regardless of whether collections are intended to be supported, given the non-descriptive error).

Given that, we can add/extend tests for:

ItemWithFlattenedValue
ItemWithNestedValue
ItemWithNestedValueHavingArraysAndCollections (collections are inside a struct, which our type handles)
BasicCrudIntegrationTests.Item

Partially implemented suggestion (excludes ItemWithNestedValueHavingArraysAndCollections): 4fc30d2

[stIncMale]

Done in c78dcde. I based this commit on your commit (and there is credit for that), but I changed a fair bit.

Discussing it over Zoom may be faster.

[vbabanin]

LGTM!

[stIncMale]

More conflicts with main, caused by #138. Requested re-review.