gril/aidl/2.1/compatibility_matrix.xml

<compatibility-matrix version="1.0" type="framework">
    <hal format="aidl" optional="true">
        <name>vendor.google.radio_ext</name>
        <version>3</version>
        <interface>
            <name>IRadioExt</name>
            <instance>default</instance>
        </interface>
    </hal>
</compatibility-matrix>