Groovy portlet.xml shows references describing Ruby for init and Action. Find the trace of portlet.xml below:

<?xml version='1.0' encoding='UTF-8' ?>
<portlet-app xmlns='http://java.sun.com/xml/ns/portlet/portlet-app_2_0.xsd' xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance' 
xsi:schemaLocation='http://java.sun.com/xml/ns/portlet/portlet-app_2_0.xsd http://java.sun.com/xml/ns/portlet/portlet-app_2_0.xsd' version='2.0'>
	<portlet>
		<description>HelloGroovy</description>
		<portlet-name>HelloGroovy</portlet-name>
		<display-name>HelloGroovy</display-name>
		<portlet-class>com.liferay.util.bridges.groovy.GroovyPortlet</portlet-class>
		<init-param>
			<description>Portlet Init View Page</description>
			<name>view-file</name>
			<value>/WEB-INF/groovy/HelloGroovy.groovy</value>
		</init-param>
		<init-param>
			<description>Portlet Ruby Action Page</description>
			<name>action-file</name>
			<value>/WEB-INF/groovy/HelloGroovy_action.groovy</value>
		</init-param>
		<init-param>
			<description>Global ruby files</description>
			<name>global-files</name>
			<value>/WEB-INF/groovy/global/custom.groovy,/WEB-INF/groovy/global/liferay_portlet.groovy</value>
		</init-param>
		<expiration-cache>0</expiration-cache>
		<supports>
			<mime-type>text/html</mime-type>
			<portlet-mode>VIEW</portlet-mode>
		</supports>
		<supported-locale>en</supported-locale>
		<resource-bundle>messages</resource-bundle>
		<portlet-info>
			<title>HelloGroovy</title>
			<short-title>HelloGroovy</short-title>
		</portlet-info>
	</portlet>
</portlet-app>