code: @Nullable
    public JAXBContext getFromCache (@Nonnull final Class <?> aClass)
    {
      return getFromCache (aClass, (ClassLoader) null);
    }
docs: Get the {@link JAXBContext} from an existing {@link Class} object. If the
  class's owning package is a valid JAXB package, this method redirects to
  {@link #getFromCache(Package)} otherwise a new JAXB context is created and
  NOT cached.
  
  @param aClass
  The class for which the JAXB context is to be created. May not be
  <code>null</code>.
  @return May be <code>null</code>.