code: protected boolean isMavenResourceDirectory(IPackageFragment packageFragment) throws JavaModelException {
  		if (packageFragment.getKind() == IPackageFragmentRoot.K_SOURCE) {
  			// check whether this pkg can be opened
  			try {
  				IResource underlyingResource = packageFragment
  						.getUnderlyingResource();
  				if (underlyingResource != null
  						&& underlyingResource.isAccessible()) {
  					return Util.isExcluded(packageFragment);
  				}
  			} catch (JavaModelException e) {
  				// resource not available
  			}
  		}
  		return false;
  	}
docs: Returns <code>true</code> if the given {@link IPackageFragment} contains
  source files, its underlying {@link IResource} is accessible and it is
  excluded from its root's classpath.