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/preferences/JavadocConfigurationPropertyPage.java
import org.eclipse.jdt.core.IJavaElement;
import org.eclipse.jdt.core.IJavaProject;
import org.eclipse.jdt.core.IPackageFragmentRoot;
import org.eclipse.jdt.core.JavaCore;
import org.eclipse.jdt.core.JavaModelException;
import org.eclipse.jdt.internal.corext.util.JavaModelUtil;
import org.eclipse.jdt.ui.JavaUI;
import org.eclipse.jdt.internal.ui.IJavaHelpContextIds;
import org.eclipse.jdt.internal.ui.JavaPlugin;
import org.eclipse.jdt.internal.ui.dialogs.StatusUtil;
import org.eclipse.jdt.internal.ui.util.ExceptionHandler;
import org.eclipse.jdt.internal.ui.wizards.IStatusChangeListener;
import org.eclipse.jdt.internal.ui.wizards.buildpaths.ArchiveFileFilter;
import org.eclipse.jdt.internal.ui.wizards.buildpaths.BuildPathSupport;
import org.eclipse.jdt.internal.ui.wizards.buildpaths.CPListElement;
/**
 * Property page used to set the project's Javadoc location for sources
 */
public class JavadocConfigurationPropertyPage extends PropertyPage implements IStatusChangeListener {
	public static final String PROP_ID= "org.eclipse.jdt.ui.propertyPages.JavadocConfigurationPropertyPage"; 
	
	private JavadocConfigurationBlock fJavadocConfigurationBlock;
	private boolean fIsValidElement;
	
	private IPath fContainerPath;
	private IClasspathEntry fEntry;
	private URL fInitalLocation;
	public JavadocConfigurationPropertyPage() {
	}
	/**