Bug 120544 [build path] Editing external source folder does not persist
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/wizards/buildpaths/CPListElement.java
fPath= path;
		fOrginalPath= path;
		fChildren= new ArrayList();
		fResource= res;
		fIsExported= false;
		
		fIsMissing= false;
		fCachedEntry= null;
		fParentContainer= parent;
		
		switch (entryKind) {
			case IClasspathEntry.CPE_SOURCE:
				createAttributeElement(OUTPUT, null, true);
				createAttributeElement(INCLUSION, new Path[0], true);
				createAttributeElement(EXCLUSION, new Path[0], true);
				break;
			case IClasspathEntry.CPE_LIBRARY:
			case IClasspathEntry.CPE_VARIABLE:
				createAttributeElement(SOURCEATTACHMENT, null, true);
				createAttributeElement(JAVADOC, null, false);
				createAttributeElement(NATIVE_LIB_PATH, null, false);
				createAttributeElement(ACCESSRULES, new IAccessRule[0], true);
				break;
			case IClasspathEntry.CPE_PROJECT:
				createAttributeElement(ACCESSRULES, new IAccessRule[0], true);
				createAttributeElement(COMBINE_ACCESSRULES, Boolean.FALSE, true); 
				break;
			case IClasspathEntry.CPE_CONTAINER:
				createAttributeElement(ACCESSRULES, new IAccessRule[0], true);
				try {