Bug 103927 [build path] External jar Dialog cannot set both Javadoc Location and Java Source Attachment in one iteration
Add an external jar to the project. From the context menu of the jar select properties. Select Javadoc location, browse to the desired location. Select Java Source Attachment. Browse to an external file. Press OK. From the context menu of the jar select properties again. Javadoc location is empty. (At this point it can be entered again without problems)
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/wizards/buildpaths/SourceAttachmentBlock.java
private IStatusChangeListener fContext;
	
	private StringButtonDialogField fFileNameField;
	private SelectionButtonDialogField fWorkspaceButton;
	private SelectionButtonDialogField fExternalFolderButton;
	
	private IStatus fNameStatus;
	
	/**
	 * The path to which the archive variable points.
	 * Null if invalid path or not resolvable. Must not exist.
	 */	
	private IPath fFileVariablePath;
		
	private IWorkspaceRoot fWorkspaceRoot;
	
	private Control fSWTWidget;
	private CLabel fFullPathResolvedLabel;
	
	private IJavaProject fProject;
	private IClasspathEntry fEntry;
	private IPath fContainerPath;
	/**
	 * @param context listeners for status updates
	 * @param entry The entry to edit