Bug 30005 Can't create linked source folder in new java project wizard [build path]
Build: I20030122 1) Open the new java project wizard 2) Enter a name, hit next 3) Click "Add Folder" on the "Source" tab. -> dialog comes up that doesn't have an option to create a new folder 4) Click cancel. Click "Browse" next to the output folder field -> this dialog allows you to create a new folder (even a linked folder) 5) Click cancel. Finish the wizard. 6) Open the java build path property page 3) Click "Add Folder" on the "Source" tab. -> now the dialog allows you to create a new linked folder. It should allow you to do this from the wizard.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/wizards/buildpaths/SourceContainerWorkbookPage.java
if (elem instanceof CPListElementAttribute) {
				CPListElementAttribute attrib= (CPListElementAttribute) elem;
				if (attrib.getKey().equals(CPListElement.EXCLUSION)) {
					if (((IPath[]) attrib.getValue()).length == 0) {
						return false;
					}
				} else if (attrib.getValue() == null) {
					return false;
				}
			} else if (elem instanceof CPListElement) {
				CPListElement curr= (CPListElement) elem;
				if (curr.getParentContainer() != null) {
					return false;
				}
			}
		}
		return true;
	}		
	
	private boolean canEdit(List selElements) {
		if (selElements.size() != 1) {
			return false;
		}
		Object elem= selElements.get(0);
		if (fFoldersList.getIndexOfElement(elem) != -1) {
			return true;
		}
		if (elem instanceof CPListElementAttribute) {
			return true;
		}