code: protected function addEndpointsSection(ArrayNodeDefinition $node)
      {
          $node->children()
              ->arrayNode('endpoints')
                  ->info('Solr Search Engine endpoint configuration')
                  ->useAttributeAsKey('endpoint_name')
                  ->performNoDeepMerging()
                  ->prototype('array')
                      ->children()
                          // To support Symfony 3 env() variables we don't parse the dsn setting here but in Endpoint ctor
                          ->scalarNode('dsn')
                              ->defaultNull()
                          ->end()
                          ->scalarNode('scheme')
                              ->defaultValue($this->defaultEndpointValues['scheme'])
                          ->end()
                          ->scalarNode('host')
                              ->defaultValue($this->defaultEndpointValues['host'])
                          ->end()
                          ->scalarNode('port')
                              ->defaultValue($this->defaultEndpointValues['port'])
                          ->end()
                          ->scalarNode('user')
                              ->defaultValue($this->defaultEndpointValues['user'])
                          ->end()
                          ->scalarNode('pass')
                              ->defaultValue($this->defaultEndpointValues['pass'])
                          ->end()
                          ->scalarNode('path')
                              ->defaultValue($this->defaultEndpointValues['path'])
                          ->end()
                          ->scalarNode('core')
                              ->isRequired()
                          ->end()
                      ->end()
                  ->end()
              ->end()
          ->end();
      }
docs: Adds endpoints definition.
  
  @param \Symfony\Component\Config\Definition\Builder\ArrayNodeDefinition $node