Backport some fixes that were part of HHH-17818, that are needed to make other backports work

Author: beikov

hibernate-core/src/main/java/org/hibernate/metamodel/mapping/internal/CaseStatementDiscriminatorMappingImpl.java

@@ -11,6 +11,7 @@
 import org.hibernate.engine.FetchTiming;
 import org.hibernate.engine.spi.SessionFactoryImplementor;
 import org.hibernate.metamodel.mapping.DiscriminatorType;
+import org.hibernate.metamodel.mapping.EntityMappingType;
 import org.hibernate.metamodel.mapping.JdbcMapping;
 import org.hibernate.metamodel.mapping.JdbcMappingContainer;
 import org.hibernate.persister.entity.JoinedSubclassEntityPersister;
@@ -88,18 +89,23 @@ public BasicFetch<?> generateFetch(
 		final TableGroup tableGroup = sqlAstCreationState.getFromClauseAccess().getTableGroup(
 				fetchParent.getNavigablePath()
 		);
-		// Since the expression is lazy, based on the available table reference joins,
-		// we need to force the initialization in case this is a fetch
-		tableDiscriminatorDetailsMap.forEach(
-				(tableName, tableDiscriminatorDetails) -> tableGroup.getTableReference(
-						fetchablePath,
-						tableName,
-						true
-				)
-		);
+		resolveSubTypeTableReferences( tableGroup, fetchablePath );
 		return super.generateFetch( fetchParent, fetchablePath, fetchTiming, selected, resultVariable, creationState );
 	}
 
+	private void resolveSubTypeTableReferences(TableGroup tableGroup, NavigablePath navigablePath) {
+		final EntityMappingType entityDescriptor = (EntityMappingType) tableGroup.getModelPart().getPartMappingType();
+		// Since the expression is lazy, based on the available table reference joins,
+		// we need to force the initialization in case this is selected
+		for ( EntityMappingType subMappingType : entityDescriptor.getSubMappingTypes() ) {
+			tableGroup.getTableReference(
+					navigablePath,
+					subMappingType.getMappedTableDetails().getTableName(),
+					true
+			);
+		}
+	}
+
 	@Override
 	public Expression resolveSqlExpression(
 			NavigablePath navigablePath,

hibernate-core/src/main/java/org/hibernate/metamodel/model/domain/internal/MappingMetamodelImpl.java

@@ -205,6 +205,10 @@ public void finishInitialization(RuntimeModelCreationContext context) {
 			registerEntityNameResolvers( persister, entityNameResolvers );
 		}
 
+		for ( EntityPersister persister : entityPersisterMap.values() ) {
+			persister.prepareLoaders();
+		}
+
 		collectionPersisterMap.values().forEach( CollectionPersister::postInstantiate );
 
 		registerEmbeddableMappingType( bootModel );

hibernate-core/src/main/java/org/hibernate/persister/entity/AbstractEntityPersister.java

@@ -3591,6 +3591,10 @@ protected String substituteBrackets(String sql) {
 	@Override
 	public final void postInstantiate() throws MappingException {
 		doLateInit();
+	}
+
+	@Override
+	public void prepareLoaders() {
 		prepareLoader( singleIdLoader );
 		prepareLoader( multiIdLoader );
 	}

hibernate-core/src/main/java/org/hibernate/persister/entity/EntityPersister.java

@@ -119,6 +119,17 @@ public interface EntityPersister extends EntityMappingType, RootTableGroupProduc
 	 */
 	void postInstantiate() throws MappingException;
 
+	/**
+	 * Prepare loaders associated with the persister.  Distinct "phase"
+	 * in building the persister after {@linkplain InFlightEntityMappingType#prepareMappingModel}
+	 * and {@linkplain #postInstantiate()} have occurred.
+	 * <p/>
+	 * The distinct phase is used to ensure that all {@linkplain org.hibernate.metamodel.mapping.TableDetails}
+	 * are available across the entire model
+	 */
+	default void prepareLoaders() {
+	}
+
 	/**
 	 * Return the {@link org.hibernate.SessionFactory} to which this persister
 	 * belongs.

hibernate-core/src/main/java/org/hibernate/persister/entity/JoinedSubclassEntityPersister.java

@@ -1273,7 +1273,8 @@ public FilterAliasGenerator getFilterAliasGenerator(String rootAlias) {
 
 	@Override
 	public TableDetails getMappedTableDetails() {
-		return getTableMapping( getTableMappings().length - 1 );
+		// Subtract the number of secondary tables (tableSpan - coreTableSpan) and get the last table mapping
+		return getTableMapping( getTableMappings().length - ( tableSpan - coreTableSpan ) - 1 );
 	}
 
 	@Override