### Eclipse Workspace Patch 1.0
#P org.eclipse.jpt.core
Index: src/org/eclipse/jpt/core/internal/resource/java/JavaResourceModelImpl.java
===================================================================
RCS file: /cvsroot/webtools/org.eclipse.jpa/components/jpa/plugins/org.eclipse.jpt.core/src/org/eclipse/jpt/core/internal/resource/java/JavaResourceModelImpl.java,v
retrieving revision 1.4
diff -u -r1.4 JavaResourceModelImpl.java
--- src/org/eclipse/jpt/core/internal/resource/java/JavaResourceModelImpl.java	15 May 2008 05:29:14 -0000	1.4
+++ src/org/eclipse/jpt/core/internal/resource/java/JavaResourceModelImpl.java	16 Jun 2008 13:50:01 -0000
@@ -85,8 +85,11 @@
 	
 	private void synchWithJavaDelta(IJavaElementDelta delta) {
 		switch (delta.getElement().getElementType()) {
-			case IJavaElement.JAVA_MODEL :
 			case IJavaElement.JAVA_PROJECT :
+				if (this.updateOnClasspathChanges(delta)) {
+					break;
+				}
+			case IJavaElement.JAVA_MODEL :
 			case IJavaElement.PACKAGE_FRAGMENT_ROOT :
 			case IJavaElement.PACKAGE_FRAGMENT :
 				this.synchChildrenWithJavaDelta(delta);
@@ -123,6 +126,18 @@
 		}
 	}
 
+	//bug 235384 - we need to update all compilation units when a classpath change occurs.
+	//The persistence.jar could have been added/removed from the classpath which affects
+	//whether we know about the jpa annotations or not.
+	private boolean updateOnClasspathChanges(IJavaElementDelta delta) {
+		if (BitTools.flagIsSet(delta.getFlags(), IJavaElementDelta.F_RESOLVED_CLASSPATH_CHANGED) ||
+			BitTools.flagIsSet(delta.getFlags(), IJavaElementDelta.F_CLASSPATH_CHANGED)) {
+				this.jpaCompilationUnit.updateFromJava();
+				return true;
+		}
+		return false;
+	}
+
 	public void updateFromResource() {
 		this.jpaCompilationUnit.updateFromJava();
 	}