### Eclipse Workspace Patch 1.0
#P org.eclipse.pde.ui
Index: src/org/eclipse/pde/internal/ui/wizards/plugin/ClasspathComputer.java
===================================================================
RCS file: /cvsroot/eclipse/org.eclipse.pde.ui/src/org/eclipse/pde/internal/ui/wizards/plugin/ClasspathComputer.java,v
retrieving revision 1.15
diff -u -r1.15 ClasspathComputer.java
--- src/org/eclipse/pde/internal/ui/wizards/plugin/ClasspathComputer.java	8 Jun 2007 16:37:10 -0000	1.15
+++ src/org/eclipse/pde/internal/ui/wizards/plugin/ClasspathComputer.java	28 Sep 2007 17:06:41 -0000
@@ -59,24 +59,22 @@
 	}
 	
 	public static IClasspathEntry[] getClasspath(IProject project, IPluginModelBase model, boolean clear) throws CoreException {
-
+		IJavaProject javaProject = JavaCore.create(project);
 		ArrayList result = new ArrayList();
-				
 		IBuild build = getBuild(project);
 
 		// add own libraries/source
 		addSourceAndLibraries(project, model, build, clear, result);
-	
+		
 		// add JRE and set compliance options
 		String ee = getExecutionEnvironment(model.getBundleDescription());	
-		result.add(createJREEntry(ee));
+		result.add(createJREEntryUsingPreviousEntry(javaProject, ee));
 		setComplianceOptions(JavaCore.create(project), ExecutionEnvironmentAnalyzer.getCompliance(ee));
 
 		// add pde container
 		result.add(createContainerEntry());
 
 		IClasspathEntry[] entries = (IClasspathEntry[]) result.toArray(new IClasspathEntry[result.size()]);
-		IJavaProject javaProject = JavaCore.create(project);
 		IJavaModelStatus validation = 
 			JavaConventions.validateClasspath(
 								javaProject, 
@@ -295,8 +293,46 @@
 		}
 	}
 	
+	/**
+	 * Returns a new classpath container entry for the given execution environment.  If the given java project
+	 * has an existing JRE/EE classpath entry, the access rules, extra attributes and isExported settings of
+	 * the existing entry will be added to the new execution entry.
+	 *  
+	 * @param javaProject project to check for existing JRE/EE classpath entries
+	 * @param ee id of the execution environment to create an entry for
+	 * @return new classpath container entry
+	 * @throws CoreException if there is a problem accessing the classpath entries of the project
+	 */
+	public static IClasspathEntry createJREEntryUsingPreviousEntry(IJavaProject javaProject, String ee) throws CoreException {
+		IClasspathEntry existingEntry = null;
+		IClasspathEntry[] entries = javaProject.getRawClasspath();
+		for (int i = 0; i < entries.length; i++) {
+			if (entries[i].getPath().segment(0).equals(JavaRuntime.JRE_CONTAINER)){
+				existingEntry = entries[i];
+				break;
+			}
+		}
+		if (existingEntry == null){
+			return createJREEntry(ee);
+		}
+		return JavaCore.newContainerEntry(getEEPath(ee), existingEntry.getAccessRules(), existingEntry.getExtraAttributes(), existingEntry.isExported());
+	}
 	
+	/**
+	 * Returns a classpath container entry for the given execution environment.
+	 * @param ee id of the execution environment
+	 * @return classpath container entry
+	 */
 	public static IClasspathEntry createJREEntry(String ee) {
+		return JavaCore.newContainerEntry(getEEPath(ee));
+	}
+		
+	/**
+	 * Returns the JRE container path for the execution environment with the given id.
+	 * @param ee execution environment id
+	 * @return JRE container path for the execution environment
+	 */
+	private static IPath getEEPath(String ee){
 		IPath path = null;
 		if (ee != null) {
 			IExecutionEnvironmentsManager manager = JavaRuntime.getExecutionEnvironmentsManager();
@@ -304,11 +340,15 @@
 			if (env != null) 
 				path = JavaRuntime.newJREContainerPath(env);
 		}
-		if (path == null)
+		if (path == null){
 			path = JavaRuntime.newDefaultJREContainerPath();
-		return JavaCore.newContainerEntry(path);
+		}
+		return path;
 	}
 	
+	/**
+	 * @return a new classpath container entry for a required plugin container
+	 */
 	public static IClasspathEntry createContainerEntry() {
 		return JavaCore.newContainerEntry(PDECore.REQUIRED_PLUGINS_CONTAINER_PATH);
 	}