ExamplePlugin.xml

<ServerManagerConfiguration>
    <ProxyGroup name="filters">
        <SourceProxy name="ExamplePlugin"
                     class="ExamplePlugin"
                     label="Example Plugin">
            <InputProperty
                    name="Input"
                    command="SetInputConnection">
                <ProxyGroupDomain name="groups">
                    <Group name="sources"/>
                    <Group name="filters"/>
                </ProxyGroupDomain>
                <DataTypeDomain name="input_type">
                    <DataType value="vtkUnstructuredGrid"/>
                </DataTypeDomain>
            </InputProperty>

            <Hints>
                <ShowInMenu category="Examples" />
            </Hints>
        </SourceProxy>
    </ProxyGroup>
</ServerManagerConfiguration>