code: @Nullable
    public JAXBContext getFromCache (@Nonnull final Package aPackage)
    {
      return getFromCache (aPackage, (ClassLoader) null);
    }
docs: Special overload with package and default {@link ClassLoader}.
  
  @param aPackage
  Package to load. May not be <code>null</code>.
  @return <code>null</code> if package is <code>null</code>.