fix issue with circularity detection

hibernate-core/src/main/java/org/hibernate/metamodel/mapping/Association.java

@@ -13,10 +13,4 @@ import org.hibernate.sql.results.graph.Fetchable;
  */
 public interface Association extends Fetchable {
 	ForeignKeyDescriptor getForeignKeyDescriptor();
-
-	/**
-	 * The column expressions that identify this association.
-	 * Mainly used in circularity detection
-	 */
-	String[] getIdentifyingColumnExpressions();
 }

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

@@ -47,7 +47,6 @@ public class EntityCollectionPart
 	private final EntityMappingType entityMappingType;
 
 	private ModelPart fkTargetModelPart;
-	private String[] identifyingColumns;
 
 	@SuppressWarnings("WeakerAccess")
 	public EntityCollectionPart(
@@ -75,14 +74,6 @@ public class EntityCollectionPart
 		else {
 			fkTargetModelPart = entityMappingType.findSubPart( fkTargetModelPartName, null );
 		}
-
-		final List<String> identifyingColumnsList = new ArrayList<>();
-		collectionDescriptor.getAttributeMapping().getKeyDescriptor().visitReferringColumns(
-				(containingTableExpression, columnExpression, jdbcMapping) -> {
-					identifyingColumnsList.add( containingTableExpression + "." + columnExpression );
-				}
-		);
-		this.identifyingColumns = identifyingColumnsList.toArray( new String[0] );
 	}
 
 
@@ -212,9 +203,4 @@ public class EntityCollectionPart
 		// todo (6.0) : this will not strictly work - we'd want a new ForeignKeyDescriptor that points the other direction
 		return collectionDescriptor.getAttributeMapping().getKeyDescriptor();
 	}
-
-	@Override
-	public String[] getIdentifyingColumnExpressions() {
-		return identifyingColumns;
-	}
 }

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

@@ -8,6 +8,7 @@ package org.hibernate.metamodel.mapping.internal;
 
 import java.util.Collections;
 import java.util.List;
+import java.util.Objects;
 import java.util.function.Consumer;
 
 import org.hibernate.HibernateException;
@@ -57,6 +58,7 @@ public class SimpleForeignKeyDescriptor implements ForeignKeyDescriptor, BasicVa
 	private final String targetColumnExpression;
 	private final JdbcMapping jdbcMapping;
 	private final ForeignKeyDirection fKeyDirection;
+	private final int hasCode;
 
 	public SimpleForeignKeyDescriptor(
 			ForeignKeyDirection fKeyDirection,
@@ -71,6 +73,13 @@ public class SimpleForeignKeyDescriptor implements ForeignKeyDescriptor, BasicVa
 		this.targetColumnContainingTable = targetColumnContainingTable;
 		this.targetColumnExpression = targetColumnExpression;
 		this.jdbcMapping = jdbcMapping;
+
+		this.hasCode = Objects.hash(
+				keyColumnContainingTable,
+				keyColumnExpression,
+				targetColumnContainingTable,
+				targetColumnExpression
+		);
 	}
 
 	@Override
@@ -405,4 +414,24 @@ public class SimpleForeignKeyDescriptor implements ForeignKeyDescriptor, BasicVa
 	public String getTargetColumnExpression() {
 		return targetColumnExpression;
 	}
+
+	@Override
+	public boolean equals(Object o) {
+		if ( this == o ) {
+			return true;
+		}
+		if ( o == null || getClass() != o.getClass() ) {
+			return false;
+		}
+		SimpleForeignKeyDescriptor that = (SimpleForeignKeyDescriptor) o;
+		return Objects.equals( keyColumnContainingTable, that.keyColumnContainingTable ) &&
+				Objects.equals( targetColumnContainingTable, that.targetColumnContainingTable ) &&
+				Objects.equals( keyColumnExpression, that.keyColumnExpression ) &&
+				Objects.equals( targetColumnExpression, that.targetColumnExpression );
+	}
+
+	@Override
+	public int hashCode() {
+		return this.hasCode;
+	}
 }

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

@@ -6,10 +6,6 @@
  */
 package org.hibernate.metamodel.mapping.internal;
 
-import java.util.ArrayList;
-import java.util.Arrays;
-import java.util.List;
-
 import org.hibernate.HibernateException;
 import org.hibernate.LockMode;
 import org.hibernate.NotYetImplementedFor6Exception;
@@ -81,11 +77,6 @@ public class SingularAssociationAttributeMapping extends AbstractSingularAttribu
 
 	private ForeignKeyDescriptor foreignKeyDescriptor;
 	private String identifyingColumnsTableExpression;
-	private String inverseIdentifyingColumnsTableExpression;
-	private String[] identifyingColumns;
-
-
-
 
 	public SingularAssociationAttributeMapping(
 			String name,
@@ -139,30 +130,14 @@ public class SingularAssociationAttributeMapping extends AbstractSingularAttribu
 		this.foreignKeyDescriptor = foreignKeyDescriptor;
 
 		final String identifyingColumnsTableExpression;
-		final String inverseColumnsTableExpression;
-		final List<String> identifyingColumnsList = new ArrayList<>();
 		if ( foreignKeyDescriptor.getDirection() == ForeignKeyDirection.FROM_PARENT && !referringPrimaryKey ) {
 			identifyingColumnsTableExpression = foreignKeyDescriptor.getTargetTableExpression();
-			inverseColumnsTableExpression = foreignKeyDescriptor.getReferringTableExpression();
-			foreignKeyDescriptor.visitTargetColumns(
-					(containingTableExpression, columnExpression, jdbcMapping) -> {
-						identifyingColumnsList.add( containingTableExpression + "." + columnExpression );
-					}
-			);
 		}
 		else {
 			identifyingColumnsTableExpression = foreignKeyDescriptor.getReferringTableExpression();
-			inverseColumnsTableExpression = foreignKeyDescriptor.getTargetTableExpression();
-			foreignKeyDescriptor.visitReferringColumns(
-					(containingTableExpression, columnExpression, jdbcMapping) -> {
-						identifyingColumnsList.add( containingTableExpression + "." + columnExpression );
-					}
-			);
 		}
 
-		this.identifyingColumns = identifyingColumnsList.toArray( new String[0] );
 		this.identifyingColumnsTableExpression = identifyingColumnsTableExpression;
-		this.inverseIdentifyingColumnsTableExpression = inverseColumnsTableExpression;
 	}
 
 	public ForeignKeyDescriptor getForeignKeyDescriptor() {
@@ -188,11 +163,6 @@ public class SingularAssociationAttributeMapping extends AbstractSingularAttribu
 		return navigableRole;
 	}
 
-	@Override
-	public String[] getIdentifyingColumnExpressions() {
-		return identifyingColumns;
-	}
-
 	@Override
 	public Fetch resolveCircularFetch(
 			NavigablePath fetchablePath,
@@ -218,7 +188,7 @@ public class SingularAssociationAttributeMapping extends AbstractSingularAttribu
 
 		final Association associationParent = (Association) referencedModePart;
 
-		if ( Arrays.equals( associationParent.getIdentifyingColumnExpressions(), this.getIdentifyingColumnExpressions() ) ) {
+		if (foreignKeyDescriptor.equals( associationParent.getForeignKeyDescriptor() ) ) {
 			// we need to determine the NavigablePath referring to the entity that the bi-dir
 			// fetch will "return" for its Assembler.  so we walk "up" the FetchParent graph
 			// to find the "referenced entity" reference

hibernate-core/src/main/java/org/hibernate/sql/results/internal/Helper.java

@@ -52,14 +52,22 @@ public class Helper {
 		if ( ResultsLogger.INSTANCE.isDebugEnabled() ) {
 			return initializer -> {
 				ResultsLogger.INSTANCE.debug( "Adding initializer : " + initializer );
-				initializers.add( initializer );
+				addIfNotPresent( initializers, initializer );
 			};
 		}
 		else {
-			return initializers::add;
+			return initializer ->
+					addIfNotPresent( initializers, initializer );
 		}
 	}
 
+	private static void addIfNotPresent(List<Initializer> initializers, Initializer initializer) {
+		if ( initializers.contains( initializer ) ) {
+			return;
+		}
+		initializers.add( initializer );
+	}
+
 	public static void finalizeCollectionLoading(
 			PersistenceContext persistenceContext,
 			CollectionPersister collectionDescriptor,

hibernate-core/src/main/java/org/hibernate/sql/results/internal/domain/BiDirectionalFetchImpl.java

@@ -155,13 +155,6 @@ public class BiDirectionalFetchImpl implements BiDirectionalFetch, Association {
 		return ( (Association) fetchParent ).getForeignKeyDescriptor();
 	}
 
-	@Override
-	public String[] getIdentifyingColumnExpressions() {
-		// fetch parent really always needs to be an Association, so we simply cast here
-		//		should maybe verify this in ctor
-		return ( (Association) fetchParent ).getIdentifyingColumnExpressions();
-	}
-
 	@Override
 	public Fetch generateFetch(
 			FetchParent fetchParent,