Bug 55340 Documentation (Javadoc) location selector does not show up with ZIP files
When having a ZIP (not JAR) file included as library there can no documentation location be selected on its properties page. When I rename the file to "*.jar" then it works.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/preferences/JavadocConfigurationPropertyPage.java
JavaPlugin.log(e);
			}
		}
		
		boolean isProject= (elem instanceof IJavaProject);
		fJavadocConfigurationBlock= new JavadocConfigurationBlock(getShell(), this, initialLocation, isProject);
		Control control= fJavadocConfigurationBlock.createContents(parent);
		control.setVisible(elem != null);
		Dialog.applyDialogFont(control);
		return control;
	}
	private IJavaElement getJavaElement() {
		IAdaptable adaptable= getElement();
		IJavaElement elem= (IJavaElement) adaptable.getAdapter(IJavaElement.class);
		if (elem == null) {
			IResource resource= (IResource) adaptable.getAdapter(IResource.class);
			
			try {
				if (resource instanceof IFile && ArchiveFileFilter.isArchivePath(resource.getFullPath())) {
					IProject proj= resource.getProject();
					if (proj.hasNature(JavaCore.NATURE_ID)) {
						IJavaProject jproject= JavaCore.create(proj);
						elem= jproject.getPackageFragmentRoot(resource); 
					}
				}
			} catch (CoreException e) {
				JavaPlugin.log(e);
			}
		}
		return elem;