JBoss.orgCommunity Documentation
First, you need to register the REST service class to the configuration file in the package named conf.portal.
<configuration xmlns="http://www.exoplaform.org/xml/ns/kernel_1_1.xsd" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.exoplaform.org/xml/ns/kernel_1_1.xsd http://www.exoplaform.org/xml/ns/kernel_1_1.xsd">
<component>
<type>org.exoplatform.services.ecm.publication.REST.presentation.document.publication.PublicationGetDocumentRESTService</type>
</component>
</configuration>