This change restores compatibility for adopters who were using this API and need their code to run on both Dali 3.0 and 3.1.  This is a short term fix which will be undone for Juno.
diff --git a/jpa/plugins/org.eclipse.jpt.jpa.core/src/org/eclipse/jpt/jpa/core/context/java/JavaPersistentType.java b/jpa/plugins/org.eclipse.jpt.jpa.core/src/org/eclipse/jpt/jpa/core/context/java/JavaPersistentType.java
index 30200d7..05654ac 100644
--- a/jpa/plugins/org.eclipse.jpt.jpa.core/src/org/eclipse/jpt/jpa/core/context/java/JavaPersistentType.java
+++ b/jpa/plugins/org.eclipse.jpt.jpa.core/src/org/eclipse/jpt/jpa/core/context/java/JavaPersistentType.java
@@ -9,6 +9,8 @@
  ******************************************************************************/
 package org.eclipse.jpt.jpa.core.context.java;
 
+import java.util.ListIterator;
+
 import org.eclipse.jpt.common.core.resource.java.JavaResourceAttribute;
 import org.eclipse.jpt.common.core.resource.java.JavaResourceType;
 import org.eclipse.jpt.common.utility.internal.iterables.ListIterable;
@@ -35,6 +37,9 @@
 	
 	ListIterable<JavaPersistentAttribute> getAttributes();
 		String ATTRIBUTES_LIST = "attributes"; //$NON-NLS-1$
+		
+	//TODO remove this compatibility method in Juno release	
+	ListIterator<JavaPersistentAttribute> attributes();	
 	
 	JavaPersistentAttribute getAttributeNamed(String attributeName);
 	
diff --git a/jpa/plugins/org.eclipse.jpt.jpa.core/src/org/eclipse/jpt/jpa/core/context/persistence/Persistence.java b/jpa/plugins/org.eclipse.jpt.jpa.core/src/org/eclipse/jpt/jpa/core/context/persistence/Persistence.java
index 6262887..a7b5215 100644
--- a/jpa/plugins/org.eclipse.jpt.jpa.core/src/org/eclipse/jpt/jpa/core/context/persistence/Persistence.java
+++ b/jpa/plugins/org.eclipse.jpt.jpa.core/src/org/eclipse/jpt/jpa/core/context/persistence/Persistence.java
@@ -9,6 +9,8 @@
  ******************************************************************************/
 package org.eclipse.jpt.jpa.core.context.persistence;
 
+import java.util.ListIterator;
+
 import org.eclipse.jpt.common.utility.internal.iterables.ListIterable;
 import org.eclipse.jpt.jpa.core.JpaStructureNode;
 import org.eclipse.jpt.jpa.core.context.XmlContextNode;
@@ -54,6 +56,9 @@
 	 */
 	ListIterable<PersistenceUnit> getPersistenceUnits();
 	
+	//TODO Remove legacy compatibility method in Juno release
+	ListIterator<PersistenceUnit> persistenceUnits();
+	
 	/**
 	 * Return the number of persistence units.
 	 */
diff --git a/jpa/plugins/org.eclipse.jpt.jpa.core/src/org/eclipse/jpt/jpa/core/context/persistence/PersistenceUnit.java b/jpa/plugins/org.eclipse.jpt.jpa.core/src/org/eclipse/jpt/jpa/core/context/persistence/PersistenceUnit.java
index aae3301..5abea75 100644
--- a/jpa/plugins/org.eclipse.jpt.jpa.core/src/org/eclipse/jpt/jpa/core/context/persistence/PersistenceUnit.java
+++ b/jpa/plugins/org.eclipse.jpt.jpa.core/src/org/eclipse/jpt/jpa/core/context/persistence/PersistenceUnit.java
@@ -9,6 +9,8 @@
  ******************************************************************************/
 package org.eclipse.jpt.jpa.core.context.persistence;
 
+import java.util.Iterator;
+
 import org.eclipse.core.resources.IFile;
 import org.eclipse.core.resources.IFolder;
 import org.eclipse.core.runtime.IPath;
@@ -300,6 +302,9 @@
 	 * both specified and implied.
 	 */
 	Iterable<ClassRef> getClassRefs();
+	
+	//TODO Remove legacy compatibility method in Juno release
+	Iterator<ClassRef> classRefs();
 
 	/**
 	 * Return the size of the persistence unit's list of class refs,
diff --git a/jpa/plugins/org.eclipse.jpt.jpa.core/src/org/eclipse/jpt/jpa/core/internal/context/java/AbstractJavaPersistentType.java b/jpa/plugins/org.eclipse.jpt.jpa.core/src/org/eclipse/jpt/jpa/core/internal/context/java/AbstractJavaPersistentType.java
index 76f65f5..94a83dd 100644
--- a/jpa/plugins/org.eclipse.jpt.jpa.core/src/org/eclipse/jpt/jpa/core/internal/context/java/AbstractJavaPersistentType.java
+++ b/jpa/plugins/org.eclipse.jpt.jpa.core/src/org/eclipse/jpt/jpa/core/internal/context/java/AbstractJavaPersistentType.java
@@ -14,6 +14,7 @@
 import java.util.HashSet;
 import java.util.Iterator;
 import java.util.List;
+import java.util.ListIterator;
 import java.util.Vector;
 import org.eclipse.core.resources.IFile;
 import org.eclipse.core.resources.IResource;
@@ -384,6 +385,11 @@
 	public ListIterable<JavaPersistentAttribute> getAttributes() {
 		return new LiveCloneListIterable<JavaPersistentAttribute>(this.attributes);
 	}
+	
+	//TODO remove this legacy compatibility method in the Juno release
+	public ListIterator<JavaPersistentAttribute> attributes() {
+		return this.getAttributes().iterator(); 
+	}
 
 	public int getAttributesSize() {
 		return this.attributes.size();
diff --git a/jpa/plugins/org.eclipse.jpt.jpa.core/src/org/eclipse/jpt/jpa/core/internal/context/persistence/AbstractPersistenceUnit.java b/jpa/plugins/org.eclipse.jpt.jpa.core/src/org/eclipse/jpt/jpa/core/internal/context/persistence/AbstractPersistenceUnit.java
index d9774c5..0b6c1bb 100644
--- a/jpa/plugins/org.eclipse.jpt.jpa.core/src/org/eclipse/jpt/jpa/core/internal/context/persistence/AbstractPersistenceUnit.java
+++ b/jpa/plugins/org.eclipse.jpt.jpa.core/src/org/eclipse/jpt/jpa/core/internal/context/persistence/AbstractPersistenceUnit.java
@@ -736,7 +736,12 @@
 	public int getClassRefsSize() {
 		return this.getSpecifiedClassRefsSize() + this.getImpliedClassRefsSize();
 	}
-
+	
+	// ********** legacy compatibility methods *********
+	//TODO remove this compatibility method in Juno release
+	public Iterator<ClassRef> classRefs() {
+		return this.getClassRefs().iterator();
+	}
 
 	// ********** specified class refs **********
 
diff --git a/jpa/plugins/org.eclipse.jpt.jpa.core/src/org/eclipse/jpt/jpa/core/internal/jpa1/context/persistence/GenericPersistence.java b/jpa/plugins/org.eclipse.jpt.jpa.core/src/org/eclipse/jpt/jpa/core/internal/jpa1/context/persistence/GenericPersistence.java
index 1e90832..c84b598 100644
--- a/jpa/plugins/org.eclipse.jpt.jpa.core/src/org/eclipse/jpt/jpa/core/internal/jpa1/context/persistence/GenericPersistence.java
+++ b/jpa/plugins/org.eclipse.jpt.jpa.core/src/org/eclipse/jpt/jpa/core/internal/jpa1/context/persistence/GenericPersistence.java
@@ -10,6 +10,8 @@
 package org.eclipse.jpt.jpa.core.internal.jpa1.context.persistence;
 
 import java.util.List;
+import java.util.ListIterator;
+
 import org.eclipse.jpt.common.core.utility.TextRange;
 import org.eclipse.jpt.common.utility.internal.iterables.EmptyListIterable;
 import org.eclipse.jpt.common.utility.internal.iterables.ListIterable;
@@ -164,6 +166,12 @@
 		return this.getContextNodeFactory().buildPersistenceUnit(this, xmlPersistenceUnit);
 	}
 
+	// ********** legacy compatibility methods **********
+	
+	//TODO Remove this compatibility method on Juno release
+	public ListIterator<PersistenceUnit> persistenceUnits() {
+		return this.getPersistenceUnits().iterator();
+	}
 
 	// ********** metamodel **********