KnpMenuBundle add icon/glyphicon - symfony

Question

I have tried to set an icon next to the link of the menu generated by knpMenuBundle but no way to get it.
I found some solutions like ->setAttribute or ->setExtra, but I can't make it work.
Do I have to add specific lines to the base template of knp ?
Do something special in the twig render ?
Here is what I have tried so far:
//Builder.php
$public function mainMenu(FactoryInterface $factory, array $options)
{
$menu = $factory->createItem('root');
$menu->setChildrenAttribute('class', 'nav navbar-nav ');
$menu->addChild('Mes Informations',['route' => 'espace_client_mesInformations'])
->setAttribute('icon','fa fa-home');
$menu->addChild('Mes Factures', array('route' => 'espace_client_mesFactures'));
$menu->addChild('Mon Extrait de Compte', array('route' => 'espace_client_mesReglements'));
$menu->addChild('Mes Services', array('route' => 'espace_client_mesServices'));
$menu->addChild('Mes Consommations', array('route' => 'espace_client_mesConsommations'));
$menu['Mes Consommations']->addChild('Télephone', array('route' => 'espace_client_mesConsoTelephone'));
$menu['Mes Consommations']->addChild('Internet', array('route' => 'espace_client_mesConsoInternet'));
$menu->addChild('Mes Liens Directs', array('route' => 'espace_client_mesLiens'));
return $menu;
}
//menu.html.twig
<div class="panel panel-default">
<div class="panel-heading">
<center><h4> Menu </h4></center>
</div>
<div class="panel-body">
{{ knp_menu_render('EspaceClientBundle:Builder:mainMenu',{'currentAsLink':false, 'template': 'EspaceClientBundle:Menu:knp_menu.html.twig'}) }}
</div>
If anyone have an answer ?
Thanks.
Edit:
I'm a little bit confused by the different files of the bundle, I must have a problem in my php code so there is the content of them:
//knp_menu.html.twig:
{% extends 'knp_menu_base.html.twig' %}
{% macro attributes(attributes) %}
{% for name, value in attributes %}
{%- if value is not none and value is not same as(false) -%}
{{- ' %s="%s"'|format(name, value is same as(true) ? name|e : value|e)|raw -}}
{%- endif -%}
{%- endfor -%}
{% endmacro %}
{% block compressed_root %}
{% spaceless %}
{{ block('root') }}
{% endspaceless %}
{% endblock %}
{% block root %}
{% set listAttributes = item.childrenAttributes %}
{{ block('list') -}}
{% endblock %}
{% block list %}
{% if item.hasChildren and options.depth is not same as(0) and item.displayChildren %}
{% import _self as knp_menu %}
<ul{{ knp_menu.attributes(listAttributes) }}>
{{ block('children') }}
</ul>
{% endif %}
{% endblock %}
{% block children %}
{# save current variables #}
{% set currentOptions = options %}
{% set currentItem = item %}
{# update the depth for children #}
{% if options.depth is not none %}
{% set options = options|merge({'depth': currentOptions.depth - 1}) %}
{% endif %}
{# update the matchingDepth for children #}
{% if options.matchingDepth is not none and options.matchingDepth > 0 %}
{% set options = options|merge({'matchingDepth': currentOptions.matchingDepth - 1}) %}
{% endif %}
{% for item in currentItem.children %}
{{ block('item') }}
{% endfor %}
{# restore current variables #}
{% set item = currentItem %}
{% set options = currentOptions %}
{% endblock %}
{% block item %}
{% if item.displayed %}
{# building the class of the item #}
{%- set classes = item.attribute('class') is not empty ? [item.attribute('class')] : [] %}
{%- if matcher.isCurrent(item) %}
{%- set classes = classes|merge([options.currentClass]) %}
{%- elseif matcher.isAncestor(item, options.matchingDepth) %}
{%- set classes = classes|merge([options.ancestorClass]) %}
{%- endif %}
{%- if item.actsLikeFirst %}
{%- set classes = classes|merge([options.firstClass]) %}
{%- endif %}
{%- if item.actsLikeLast %}
{%- set classes = classes|merge([options.lastClass]) %}
{%- endif %}
{# Mark item as "leaf" (no children) or as "branch" (has children that are displayed) #}
{% if item.hasChildren and options.depth is not same as(0) %}
{% if options.branch_class is not empty and item.displayChildren %}
{%- set classes = classes|merge([options.branch_class]) %}
{% endif %}
{% elseif options.leaf_class is not empty %}
{%- set classes = classes|merge([options.leaf_class]) %}
{%- endif %}
{%- set attributes = item.attributes %}
{%- if classes is not empty %}
{%- set attributes = attributes|merge({'class': classes|join(' ')}) %}
{%- endif %}
{# displaying the item #}
{% import _self as knp_menu %}
<li{{ knp_menu.attributes(attributes) }}>
{%- if item.uri is not empty and (not matcher.isCurrent(item) or options.currentAsLink) %}
{{ block('linkElement') }}
{%- else %}
{{ block('spanElement') }}
{%- endif %}
{# render the list of children#}
{%- set childrenClasses = item.childrenAttribute('class') is not empty ? [item.childrenAttribute('class')] : [] %}
{%- set childrenClasses = childrenClasses|merge(['menu_level_' ~ item.level]) %}
{%- set listAttributes = item.childrenAttributes|merge({'class': childrenClasses|join(' ') }) %}
{{ block('list') }}
</li>
{% endif %}
{% endblock %}
{% block linkElement %}
{% import "knp_menu.html.twig" as macros %}
<a href="{{ item.uri }}"{{ macros.attributes(item.linkAttributes) }}>
<span class="icon">{{ item.getExtra('icon') }}</span>
<span class="entry">{{ block('label') }}</span>
</a>
{% endblock %}
{% block spanElement %}{% import _self as knp_menu %}<span{{ knp_menu.attributes(item.labelAttributes) }}>{{ block('label') }}</span>{% endblock %}

Answer 1

You should edit your menu template EspaceClientBundle:Menu:knp_menu.html.twig like:
{% block label %}
{% if options.allow_safe_labels and item.getExtra('safe_label', false) %}
{{ item.label|raw|trans }}
{% else %}
{{ item.label }}
{% endif %}
{% if item.extras.icon is defined %}
<i class="{{ item.extras.icon }}"></i>
{% endif %}
{% endblock %}
I recommend you, to delete the whitespaces between twig tags.
Then, in menu builder:
$menu->addChild('Mes Informations', [
'route' => 'espace_client_mesInformations',
'extras' => ['icon' => 'fa fa-home']
]);