No target validator set | Spring Boot Application on Google App Engine

The example seems to have problem. When starting the app on GAE an error like that is printed. Caused by "no target validator set". On local google app engine it is working. Any help?

[s~hsr-cloud-solutions-work/20180511t100939.409639534574068310].: 2018-05-11 08:12:19.222 WARN 1 --- [RequestD8018BA4] ationConfigEmbeddedWebApplicationContext : Exception encountered during context initialization - cancelling refresh attempt: org.springframework.context.ApplicationContextException: Unable to start embedded container; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'cxfServletRegistration' defined in class path resource [org/apache/cxf/spring/boot/autoconfigure/CxfAutoConfiguration.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.boot.web.servlet.ServletRegistrationBean]: Factory method 'cxfServletRegistration' threw exception; nested exception is java.lang.IllegalStateException: No target Validator set