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
private boolean canUpdateContainer() {
		if (fEntryKind == IClasspathEntry.CPE_CONTAINER && fProject != null) {
			ClasspathContainerInitializer initializer= JavaCore.getClasspathContainerInitializer(fPath.segment(0));
			return (initializer != null && initializer.canUpdateClasspathContainer(fPath, fProject));
		}
		return false;
	}
	
	public boolean isInNonModifiableContainer() {
		if (fParentContainer instanceof CPListElement) {
			return !((CPListElement) fParentContainer).canUpdateContainer();
		}
		return false;
	}
	
	
	/*
	 * @see Object#equals(java.lang.Object)
	 */
	public boolean equals(Object other) {
		if (other != null && other.getClass().equals(getClass())) {
			CPListElement elem= (CPListElement) other;
			return getClasspathEntry().equals(elem.getClasspathEntry());
		}
		return false;
	}
    	
	/*
	 * @see Object#hashCode()