Editable p:selectOneMenu - jsf

Question

How to set placeholder in editable <p:selectOneMenu>?
In editable <p:selectOneMenu> of PrimeFaces, initial UI looks as below:
http://www.primefaces.org/showcase/ui/input/oneMenu.xhtml
(see the editable menu)
Is there a way to place a placeholder which says text like "Click to enter manual input" or to make user aware that this dropdown is editable.
Find the code snippet below for reference.
<div class="setupDataSection">
<div class="pageCenter pageCenterShortened">
<div style="float: left;" class="sectionTitle sectionTitleInline">
<h:outputLabel value="Tenant "/>
</div>
<div style="float: left; padding-left: 40px;">
<p:selectOneMenu id="tenant"
styleClass="ddlPOS"
style="width: 190px;"
label="Tenant"
value="#{onBoardingAction.selTenant}"
editable="true">
<p:watermark for="tenant"
value="Search with a keyword"
id="watermark" />
<f:selectItem itemLabel="Add new tenant" />
<f:selectItems value="#{onBoardingAction.tenants}" />
<p:ajax event="change"
execute="#this"
update="tenant region POS"
listener="#{onBoardingAction.settingRegions()}" />
</p:selectOneMenu>
</div>
</div>
</div>

Answer 1

Primefaces call it watermark SEE, If your SelectOneMenu is empty this water martk's text automatically appears
<p:watermark for="fileSize" value="Search with a keyword" id="watermark" />
Update
I have tested your code and It work fine for me if you are using template maybe your CSS overriding component try this, I just put p:watermark outside the component code:
<f:selectItem itemLabel="Add new tenant" />
<f:selectItems value="#{onBoardingAction.tenants}" />
<p:ajax event="change"
execute="#this"
update="tenant region POS""
listener="#{onBoardingAction.settingRegions()}" />
</p:selectOneMenu>
<p:watermark for="tenant"
value="Search with a keyword"
id="watermark" />
HOPE RESOLVED :)