Bug 114774 [javadoc location] validate does not work with ! in path
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/preferences/JavadocConfigurationBlock.java
if (folder.isDirectory()) {
				File indexFile= new File(folder, "index.html"); 
				if (indexFile.isFile()) {				
					File packageList= new File(folder, "package-list"); 
					if (packageList.exists()) {
						if (MessageDialog.openConfirm(fShell, fTitle, fValidMessage)) { 
							spawnInBrowser(indexFile.toURL());
						}
						return;					
					}
				}
			}
			MessageDialog.openWarning(fShell, fTitle, fInvalidMessage); 
		}
		
		private void validateURL(URL location) throws MalformedURLException {
			IPath path= new Path(location.toExternalForm());
			IPath index = path.append("index.html"); 
			IPath packagelist = path.append("package-list"); 
			URL indexURL = new URL(index.toString());
			URL packagelistURL = new URL(packagelist.toString());
			boolean suc= checkURLConnection(indexURL) && checkURLConnection(packagelistURL);
			if (suc) {
				if (MessageDialog.openConfirm(fShell, fTitle, fValidMessage))
					spawnInBrowser(indexURL);
			} else { 
				MessageDialog.openWarning(fShell, fTitle, fInvalidMessage);
			}
		}
	}