How to validate two composite component fields in JSF? - validation

Question

I have two input date fields startDate & endDate based on same composite component 'comps:dateTimeZone'.
inputpage.xhtml
<div>
<comps:dateTimeZone id="startDate" date="#{myBean.startDate}">
</comps:dateTimeZone>
<comps:dateTimeZone id="endDate" date="#{myBean.endDate}">
</comps:dateTimeZone>
</div>
Need to validate
if one is present, then other is also present.
the interval/difference is within 15 days.
dateTimeZone.xhtml
<cc:interface>
<cc:attribute name="date" type="java.util.Date" required="true"/>
<cc:attribute name="timeZoneName" type="java.lang.String" required="false"/>
</cc:interface>
<cc:implementation>
<h:inputText id="date-input"
value="#{cc.attrs.date}"
required="true"
requiredMessage="Date is required."
immediate="true">
<f:converter converterId="dateTimeZoneConverter" />
<f:attribute name="dateTimeZone" value="#{cc.attrs.timeZoneName}"/>
</h:inputText>
</cc:implementation>
Since both are based on composite component, the usual approach with
inputpage.xhtml having
<comps:dateTimeZone id="endDate" date="#{myBean.endDate}">
<f:validator validatorId="daterangevalidator" for="dateinputfieldref"/>
</comps:dateTimeZone>
dateTimeZone.xhtml having
<cc:editableValueHolder name="dateinputfieldref" targets="date-input" />
DateRangeValidator.java having
#FacesValidator("dateRangeValidator")
public class DateRangeValidator implements Validator {
#Override
public void validate(FacesContext facesContext, UIComponent uiComponent, Object value) throws ValidatorException {
final Date endDateValue = (Date) value;
//Below doesn't work as uiComponent is tied to only endDate.
final Date startDateValue = (Date) uiComponent.getAttributes().get("startDate");
}
}
doesn't seem to help. It is bound to only one field at a time. So unable to get access to the other field 'startDate'.
Pls suggest how to perform this validation based on 2 date fields. How to get handle of both the fields at the same time ? like
if(startDate!=null & endDate==null){
return valid;
}
if (endDate-StartDate > 15days){
return invalid;
}