HHH-19977 Relax scopes to allow HR to run a reactive flush

A native query might need to run a flush operation before
it's executed. Hibernate Reactive have to run a reactive flush.

By relaxing the scopes of these methods, we can avoid
some code duplication.

Author: DavideD

hibernate-core/src/main/java/org/hibernate/query/spi/AbstractSelectionQuery.java

@@ -180,16 +180,28 @@ protected void beforeQuery() {
 
 		session.prepareForQueryExecution( requiresTxn( options.getLockOptions().getLockMode() ) );
 		prepareForExecution();
+		prepareSessionFlushMode( session );
+		prepareSessionCacheMode( session );
+	}
 
-		assert sessionFlushMode == null;
-		assert sessionCacheMode == null;
 
+	/*
+	 * Used by Hibernate Reactive
+	 */
+	protected void prepareSessionFlushMode(SharedSessionContractImplementor session) {
+		assert sessionFlushMode == null;
 		final var effectiveFlushMode = getQueryOptions().getFlushMode();
 		if ( effectiveFlushMode != null && session instanceof SessionImplementor statefulSession ) {
 			sessionFlushMode = statefulSession.getHibernateFlushMode();
 			statefulSession.setHibernateFlushMode( effectiveFlushMode );
 		}
+	}
 
+	/*
+	 * Used by Hibernate Reactive
+	 */
+	protected void prepareSessionCacheMode(SharedSessionContractImplementor session) {
+		assert sessionCacheMode == null;
 		final var effectiveCacheMode = getCacheMode();
 		if ( effectiveCacheMode != null ) {
 			sessionCacheMode = session.getCacheMode();

hibernate-core/src/main/java/org/hibernate/query/sql/internal/NativeQueryImpl.java

@@ -722,14 +722,17 @@ protected void prepareForExecution() {
 				getSession().flush();
 			}
 			// Reset the callback before every execution
-			callback = null;
+			resetCallback();
 		}
 		// Otherwise, the application specified query spaces via the Hibernate
 		// SynchronizeableQuery and so the query will already perform a partial
 		// flush according to the defined query spaces - no need for a full flush.
 	}
 
-	private boolean shouldFlush() {
+	/*
+	 * Used by Hibernate Reactive
+	 */
+	protected boolean shouldFlush() {
 		if ( getSession().isTransactionInProgress() ) {
 			final var flushMode = getQueryOptions().getFlushMode();
 			return switch ( flushMode == null ? getSession().getHibernateFlushMode() : flushMode ) {