Capítulo 8(fechamento da compra e processamento assíncrono)

Ao tenta efetuar a compra me deparo com:

Error processing request
Context Path:/casadocodigo
Servlet Path:/site/checkout.xhtml
Path Info:null
Query String:null
Stack Trace
javax.servlet.ServletException: Validation group not found: br.com.casadocodigo.loja.models.validation.loja.groups.BuyerGroup
javax.faces.webapp.FacesServlet.service(FacesServlet.java:659)
io.undertow.servlet.handlers.ServletHandler.handleRequest(ServletHandler.java:85)
io.undertow.servlet.handlers.security.ServletSecurityRoleHandler.handleRequest(ServletSecurityRoleHandler.java:61)
io.undertow.servlet.handlers.ServletDispatchingHandler.handleRequest(ServletDispatchingHandler.java:36)
org.wildfly.extension.undertow.security.SecurityContextAssociationHandler.handleRequest(SecurityContextAssociationHandler.java:78)
io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
io.undertow.servlet.handlers.security.SSLInformationAssociationHandler.handleRequest(SSLInformationAssociationHandler.java:131)
io.undertow.servlet.handlers.security.ServletAuthenticationCallHandler.handleRequest(ServletAuthenticationCallHandler.java:56)
io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
io.undertow.security.handlers.AbstractConfidentialityHandler.handleRequest(AbstractConfidentialityHandler.java:45)
io.undertow.servlet.handlers.security.ServletConfidentialityConstraintHandler.handleRequest(ServletConfidentialityConstraintHandler.java:63)
io.undertow.security.handlers.AuthenticationMechanismsHandler.handleRequest(AuthenticationMechanismsHandler.java:58)
io.undertow.servlet.handlers.security.CachedAuthenticatedSessionHandler.handleRequest(CachedAuthenticatedSessionHandler.java:70)
io.undertow.security.handlers.SecurityInitialHandler.handleRequest(SecurityInitialHandler.java:76)
io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
org.wildfly.extension.undertow.security.jacc.JACCContextIdHandler.handleRequest(JACCContextIdHandler.java:61)
io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
io.undertow.servlet.handlers.ServletInitialHandler.handleFirstRequest(ServletInitialHandler.java:261)
io.undertow.servlet.handlers.ServletInitialHandler.dispatchRequest(ServletInitialHandler.java:247)
io.undertow.servlet.handlers.ServletInitialHandler.access$000(ServletInitialHandler.java:76)
io.undertow.servlet.handlers.ServletInitialHandler$1.handleRequest(ServletInitialHandler.java:166)
io.undertow.server.Connectors.executeRootHandler(Connectors.java:197)
io.undertow.server.HttpServerExchange$1.run(HttpServerExchange.java:759)
java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
java.lang.Thread.run(Thread.java:748)