I was using a code from my teacher when I found this error. I tried to search in google how to solve it, just with this page: java lang classnotfoundexception .com.google.api.server.spi.endpointservlet. I just applied what the answers said but the problem didn't solve. What I should do to solve this error?

com.google.api.server.spi.EndpointsServlet could not be resolved    web.xml /cuentavocales/src/main/webapp/WEB-INF  line 8  Unresolved Servlet Class