You need to check in the required
attribute if the other inputs have submitted a non-empty value. Since this can result in quite some boilerplate, here's a kickoff example with only 3 input components.
<h:form id="form">
<h:inputText id="input1" value="#{bean.input1}" required="#{empty param['form:input2'] and empty param['form:input3']}" />
<h:inputText id="input2" value="#{bean.input2}" required="#{empty param['form:input1'] and empty param['form:input3']}" />
<h:inputText id="input3" value="#{bean.input3}" required="#{empty param['form:input1'] and empty param['form:input2']}" />
</h:form>
An alternative is to bind the components to the view and use UIInput#getValue()
to check the value of the previous components and UIInput#getSubmittedValue()
to check them for next components (components are namely processed in the order as they appear in the component tree). This way you don't need to hardcode client ID's. You only need to ensure that binding names doesn't conflict with existing managed bean names.
<h:inputText binding="#{input1}" value="#{bean.input1}" required="#{empty input2.submittedValue and empty input3.submittedValue}" />
<h:inputText binding="#{input2}" value="#{bean.input2}" required="#{empty input1.value and empty input3.submittedValue}" />
<h:inputText binding="#{input3}" value="#{bean.input3}" required="#{empty input1.value and empty input2.value}" />
You'll understand that this produces ugly boilerplate when you have more and more components. The JSF utility library OmniFaces has a <o:validateAllOrNone>
validator for the exact purpose. See also the live demo. Based on your quesiton tags, you're using OmniFaces, so you should already be set with just this:
<o:validateAllOrNone components="input1 input2 input3" />
<h:inputText id="input1" value="#{bean.input1}" />
<h:inputText id="input2" value="#{bean.input2}" />
<h:inputText id="input3" value="#{bean.input3}" />