code: @Nonnull
    public static IReadableResource getResolvedResource (@Nullable final String sSystemId,
                                                         @Nullable final String sBaseURI)
    {
      return getResolvedResource (sSystemId, sBaseURI, (ClassLoader) null);
    }
docs: Do the standard resource resolving of sSystemId relative to sBaseURI
  
  @param sSystemId
  The resource to search. May be <code>null</code> if base URI is set.
  @param sBaseURI
  The base URI from where the search is initiated. May be
  <code>null</code> if systemId is set.
  @return The non-<code>null</code> resource. May be non-existing!
  @throws UncheckedIOException
  In case the file resolution (to an absolute file) fails.