code: public void setNamespaceURI(String prefix, String namespaceURI) {
      if (prefix == null)
        throw new IllegalArgumentException("Cannot bind null prefix");
      if (namespaceURI == null)
        throw new IllegalArgumentException("Cannot set prefix to null namespace URI");
  
      // no need to store
      if (XMLConstants.XML_NS_PREFIX.equals(prefix) || XMLConstants.XMLNS_ATTRIBUTE.equals(prefix))
        return;
  
      bindings.put(prefix, namespaceURI);
    }
docs: Specifies a binding between a prefix and a namespace URI.
  @param prefix	the prefix for the binding
  @param namespaceURI	the URI for the namespace