protected List<MessageHandler> getOutboundPayloadHandlers() throws ComponentInitializationException {
        final List<MessageHandler> handlers = new ArrayList<>();
        handlers.add(buildSAMLProtocolAndRoleHandler(SPSSODescriptor.DEFAULT_ELEMENT_NAME));
        handlers.add(buildSAMLMetadataLookupHandler(spMetadataResolver));
        handlers.add(buildPopulateSignatureSigningParametersHandler());
        handlers.add(buildSAMLOutboundProtocolMessageSigningHandler());
        return handlers;
    }
<p>getOutboundPayloadHandlers.</p>

@return a {@link List} object
@throws ComponentInitializationException if any.
pac4j-saml/src/main/java/org/pac4j/saml/sso/artifact/DefaultSOAPPipelineFactory.java