Nested Multifield (coral 3) with Sling Model in AEM

Create AEM multi module project using archtype 11

Create a new component with cq:dialog for Touch UI as shown below.

<?xml version="1.0" encoding="UTF-8"?>
<jcr:root xmlns:sling="http://sling.apache.org/jcr/sling/1.0" xmlns:cq="http://www.day.com/jcr/cq/1.0" xmlns:jcr="http://www.jcp.org/jcr/1.0" xmlns:nt="http://www.jcp.org/jcr/nt/1.0"
    jcr:primaryType="nt:unstructured"
    jcr:title="Country Details"
    sling:resourceType="cq/gui/components/authoring/dialog">
    <content
        jcr:primaryType="nt:unstructured"
        sling:resourceType="granite/ui/components/coral/foundation/fixedcolumns">
        <items jcr:primaryType="nt:unstructured">
            <column
                jcr:primaryType="nt:unstructured"
                sling:resourceType="granite/ui/components/coral/foundation/container">
                <items jcr:primaryType="nt:unstructured">
                    <countries
                        jcr:primaryType="nt:unstructured"
                        sling:resourceType="granite/ui/components/coral/foundation/form/multifield"
                        composite="{Boolean}true"
                        fieldLabel="Countries">
                        <field
                            jcr:primaryType="nt:unstructured"
                            sling:resourceType="granite/ui/components/coral/foundation/container"
                            name="./countries">
                            <items jcr:primaryType="nt:unstructured">
                                <column
                                    jcr:primaryType="nt:unstructured"
                                    sling:resourceType="granite/ui/components/coral/foundation/container">
                                    <items jcr:primaryType="nt:unstructured">
                                        <countryName
                                            jcr:primaryType="nt:unstructured"
                                            sling:resourceType="granite/ui/components/coral/foundation/form/textfield"
                                            fieldLabel="Country Name"
                                            name="./countryName"/>                                        
                                        <states
                                            jcr:primaryType="nt:unstructured"
                                            sling:resourceType="granite/ui/components/coral/foundation/form/multifield"
                                            composite="{Boolean}true"
                                            fieldLabel="States">
                                            <field
                                                jcr:primaryType="nt:unstructured"
                                                sling:resourceType="granite/ui/components/coral/foundation/container"
                                                name="./states">
                                                <items jcr:primaryType="nt:unstructured">
                                                    <column
                                                        jcr:primaryType="nt:unstructured"
                                                        sling:resourceType="granite/ui/components/coral/foundation/container">
                                                        <items jcr:primaryType="nt:unstructured">
                                                            <stateName
                                                                jcr:primaryType="nt:unstructured"
                                                                sling:resourceType="granite/ui/components/coral/foundation/form/textfield"
                                                                fieldLabel="State Name"
                                                                name="./stateName"/>
                                                            <statePostal
                                                                jcr:primaryType="nt:unstructured"
                                                                sling:resourceType="granite/ui/components/coral/foundation/form/textfield"
                                                                fieldLabel="State Postal"
                                                                name="./statePostal"/>
                                                            <statePopulation
                                                                jcr:primaryType="nt:unstructured"
                                                                sling:resourceType="granite/ui/components/coral/foundation/form/numberfield"
                                                                fieldLabel="State Population"
                                                                name="./statePopulation"/>
                                                            <stateDensity
                                                                jcr:primaryType="nt:unstructured"
                                                                sling:resourceType="granite/ui/components/coral/foundation/form/select"
                                                                fieldDescription="Select State Density"
                                                                fieldLabel="State Density"
                                                                name="./stateDensity">
                                                                <items jcr:primaryType="nt:unstructured">
                                                                    <high
                                                                        jcr:primaryType="nt:unstructured"
                                                                        text="High"
                                                                        value="high"/>
                                                                    <medium
                                                                        jcr:primaryType="nt:unstructured"
                                                                        text="Medium"
                                                                        value="medium"/>
                                                                    <low
                                                                        jcr:primaryType="nt:unstructured"
                                                                        text="Low"
                                                                        value="low"/>                                                                    
                                                                </items>
                                                            </stateDensity>
                                                        </items>
                                                    </column>
                                                </items>
                                            </field>
                                        </states>
                                    </items>
                                </column>
                            </items>
                        </field>
                    </countries>
                </items>
            </column>
        </items>
    </content>
</jcr:root>

Now create slingmodels to get the authored values.

1. CountriesModel.java
2. Country.java
3. State.java