class DefaultExplicitIndexProvider implements IndexProviders, ExplicitIndexProvider {

    @Override
    public void registerIndexProvider( String name, IndexImplementation index )
    {
        if ( indexProviders.containsKey( name ) )
        {
            throw new IllegalArgumentException( "Index provider '" + name + "' already registered" );
        }
        indexProviders.put( name, index );
    }

}