Use of context-provider element in web-item elements

According to, context-provider element should be a valid child element for web-item elements.
We are not able to get it working on our Bamboo app as per:

<web-item key="example-settings" name="Administration section" section="system.admin/plugins">
    <tooltip key="com.example.admin.config.tooltip" />
    <context-provider class="com.example.context.admin.ConfigContext" />

Java class “com.example.context.admin.ConfigContext” seems to be not called by the system.
Any advice?
Thanks in advance.