lint/cli/src/test/java/com/android/tools/lint/checks/data/res/layout/unused_namespace.xml

<?xml version="1.0" encoding="utf-8"?>
<foo.bar.LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:unused1="http://schemas.android.com/apk/res/unused1"
    xmlns:unused2="http://schemas.android.com/apk/res/unused1"
    xmlns:unused3="http://foo.bar.com/foo"
    xmlns:notunused="http://schemas.android.com/apk/res/notunused"
    xmlns:tools="http://schemas.android.com/tools" >

    <foo.bar.Button
        notunused:foo="Foo"
        tools:ignore="HardcodedText" >
    </foo.bar.Button>

</foo.bar.LinearLayout>