IReports + JSON + subDataset

Question

"topics":[
    {
    "name":"a",
    "description":"a`"
    },
    {
    "name":"b",
    "description":"b1"
    },
    {
    "name":"c",
    "description":"c1."
    }
]

I created the following dataset.

<subDataset name="subDataset">
    <queryString language="json"><![CDATA[topics]]></queryString>
    <field name="topicname" class="java.lang.String" />
    <field name="topicdescription" class="java.lang.String" />
</subDataset>

and add the following components to the Elements

                                                                       

However, he always gives me an empty list.

Can anyone help me regarding the same.