fixed 'add virtual attribute' handler and menu item to only appear when the eclipselink-orm.xml file is version 2.1 or greater

diff --git a/jpa/plugins/org.eclipse.jpt.jpa.core/plugin.xml b/jpa/plugins/org.eclipse.jpt.jpa.core/plugin.xml
index 78a2f92..a7ae462 100644
--- a/jpa/plugins/org.eclipse.jpt.jpa.core/plugin.xml
+++ b/jpa/plugins/org.eclipse.jpt.jpa.core/plugin.xml

@@ -177,6 +177,13 @@
 			properties="isLatestSupportedVersion, isNotLatestSupportedVersion"
 			class="org.eclipse.jpt.jpa.core.internal.JptResourceModelPropertyTester"/>
 
+		<propertyTester
+			id="org.eclipse.jpt.jpa.ui.propertyTester.jpaContextNode"
+			type="org.eclipse.jpt.jpa.core.context.JpaContextNode"
+			namespace="org.eclipse.jpt.jpa.core"
+			properties="isCompatibleVersion"
+			class="org.eclipse.jpt.jpa.core.internal.JpaContextNodePropertyTester"/>
+
 	</extension>
 
 

diff --git a/jpa/plugins/org.eclipse.jpt.jpa.core/src/org/eclipse/jpt/jpa/core/internal/JpaContextNodePropertyTester.java b/jpa/plugins/org.eclipse.jpt.jpa.core/src/org/eclipse/jpt/jpa/core/internal/JpaContextNodePropertyTester.java
new file mode 100644
index 0000000..e03a735
--- /dev/null
+++ b/jpa/plugins/org.eclipse.jpt.jpa.core/src/org/eclipse/jpt/jpa/core/internal/JpaContextNodePropertyTester.java

@@ -0,0 +1,39 @@
+/*******************************************************************************
+ * Copyright (c) 2012 Oracle. All rights reserved.
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v1.0, which accompanies this distribution
+ * and is available at http://www.eclipse.org/legal/epl-v10.html.
+ * 
+ * Contributors:
+ *     Oracle - initial API and implementation
+ ******************************************************************************/
+package org.eclipse.jpt.jpa.core.internal;
+
+import org.eclipse.core.expressions.PropertyTester;
+import org.eclipse.jpt.jpa.core.JptJpaCorePlugin;
+import org.eclipse.jpt.jpa.core.context.JpaContextNode;
+
+/**
+ * Property tester for {@link JpaContextNode}.
+ * See <code>org.eclipse.jpt.jpa.core/plugin.xml</code>
+ */
+public class JpaContextNodePropertyTester
+	extends PropertyTester
+{
+	public static final String IS_COMPATIBLE_VERSION = "isCompatibleVersion"; //$NON-NLS-1$
+
+
+	public boolean test(Object receiver, String property, Object[] args, Object expectedValue) {
+		if (receiver instanceof JpaContextNode) {
+			return this.test((JpaContextNode) receiver, property, (String) expectedValue);
+		}
+		return false;
+	}
+
+	private boolean test(JpaContextNode contextNode, String property, String expectedValue) {
+		if (property.equals(IS_COMPATIBLE_VERSION)) {
+			return JptJpaCorePlugin.resourceTypeIsCompatible(contextNode.getResourceType(), expectedValue);
+		}
+		return false;
+	}
+}

diff --git a/jpa/plugins/org.eclipse.jpt.jpa.eclipselink.ui/plugin.xml b/jpa/plugins/org.eclipse.jpt.jpa.eclipselink.ui/plugin.xml
index accc7f1..3822421 100644
--- a/jpa/plugins/org.eclipse.jpt.jpa.eclipselink.ui/plugin.xml
+++ b/jpa/plugins/org.eclipse.jpt.jpa.eclipselink.ui/plugin.xml

@@ -181,15 +181,19 @@
 			commandId="org.eclipse.jpt.jpa.eclipselink.ui.persistentTypeAddVirtualAttribute"
 			class="org.eclipse.jpt.jpa.eclipselink.ui.internal.handlers.AddVirtualAttributeHandler">
 			<activeWhen>
-				<reference
-					definitionId="org.eclipse.jpt.jpa.ui.reference.inJpaStructureView">
-				</reference>
+				<and>
+					<with variable="activePartId">
+		    			<equals value="org.eclipse.jpt.ui.jpaStructureView"/>
+		   			</with>
+					<with variable="selection">
+						<count value="1"/>
+						<iterate operator="and">
+							<instanceof value="org.eclipse.jpt.jpa.eclipselink.core.context.orm.EclipseLinkOrmPersistentType"/>
+							<test property="org.eclipse.jpt.jpa.core.isCompatibleVersion" value="&apos;2.1&apos;"/>
+						</iterate>
+					</with>
+				</and>
 			</activeWhen>
-			<enabledWhen>
-				<iterate>
-					<instanceof value="org.eclipse.jpt.jpa.eclipselink.core.context.orm.EclipseLinkOrmPersistentType"/>
-				</iterate>
-			</enabledWhen>
 		</handler>
     </extension>
 
@@ -205,10 +209,11 @@
 			<command
 				commandId="org.eclipse.jpt.jpa.eclipselink.ui.persistentTypeAddVirtualAttribute">
 				<visibleWhen>
-					<with
-						variable="selection">
-						<iterate ifEmpty="false">
+					<with variable="selection">
+						<count value="1"/>
+						<iterate operator="and">
 							<instanceof value="org.eclipse.jpt.jpa.eclipselink.core.context.orm.EclipseLinkOrmPersistentType"/>
+							<test property="org.eclipse.jpt.jpa.core.isCompatibleVersion" value="&apos;2.1&apos;"/>
 						</iterate>
 					</with>
 				</visibleWhen>