code: protected final void handlePutNamespaceContextPrefixInRoot (@Nonnull final Map <QName, String> aAttrMap)
    {
      if (m_aSettings.isEmitNamespaces () &&
          m_aNSStack.size () == 1 &&
          m_aSettings.isPutNamespaceContextPrefixesInRoot ())
      {
        // The only place where the namespace context prefixes are added to the
        // root element
        for (final Map.Entry <String, String> aEntry : m_aRootNSMap.entrySet ())
        {
          aAttrMap.put (XMLHelper.getXMLNSAttrQName (aEntry.getKey ()), aEntry.getValue ());
          m_aNSStack.addNamespaceMapping (aEntry.getKey (), aEntry.getValue ());
        }
      }
    }
docs: This method handles the case, if all namespace context entries should be
  emitted on the root element.
  
  @param aAttrMap