code: @Nullable
    public JAXBContext getFromCache (@Nonnull final Package aPackage, @Nullable final ClassLoader aClassLoader)
    {
      return getFromCache (new JAXBContextCacheKey (aPackage, aClassLoader));
    }
docs: Special overload with package and {@link ClassLoader}. In this case the
  resulting value is NOT cached!
  
  @param aPackage
  Package to load. May not be <code>null</code>.
  @param aClassLoader
  Class loader to use. May be <code>null</code> in which case the
  default class loader is used.
  @return <code>null</code> if package is <code>null</code>.