gwt application not deployed to google app engine with appcfg

I have gwt 2.7 project that i develop with eclipse.
from 1.9.20 I not success to deploy project to google app engine
I deploy the project with old gwt plugin in eclipse
when the deploy finished I get error

Unable to update:
java.lang.RuntimeException: Fatal problem encountered during deployment. Please refer to the 
logs for more information.
at com.google.appengine.tools.admin.AppVersionUpload.isServing(AppVersionUpload.java:1051)
at com.google.appengine.tools.admin.AppVersionUpload.access$200(AppVersionUpload.java:43)
at com.google.appengine.tools.admin.AppVersionUpload$2.call(AppVersionUpload.java:884)
at com.google.appengine.tools.admin.AppVersionUpload$2.call(AppVersionUpload.java:881)
at com.google.appengine.tools.admin.AppVersionUpload$3.call(AppVersionUpload.java:1188)
at com.google.appengine.tools.admin.AppVersionUpload$3.call(AppVersionUpload.java:1185)
at com.google.appengine.tools.admin.AppVersionUpload.retryWithBackoffOptional(AppVersionUpload.java:1213)
at com.google.appengine.tools.admin.AppVersionUpload.retryWithBackoff(AppVersionUpload.java:1183)
at com.google.appengine.tools.admin.AppVersionUpload.commit(AppVersionUpload.java:881)
at com.google.appengine.tools.admin.AppVersionUpload.uploadFilesTransaction(AppVersionUpload.java:223)
at com.google.appengine.tools.admin.AppVersionUpload.doUpload(AppVersionUpload.java:197)
at com.google.appengine.tools.admin.AppAdminImpl.doUpdate(AppAdminImpl.java:580)
at com.google.appengine.tools.admin.AppAdminImpl.update(AppAdminImpl.java:65)
at com.google.appengine.eclipse.core.proxy.AppEngineBridgeImpl.deploy(AppEngineBridgeImpl.java:438)
at com.google.appengine.eclipse.core.deploy.DeployProjectJob.runInWorkspace(DeployProjectJob.java:158)
at org.eclipse.core.internal.resources.InternalWorkspaceJob.run(InternalWorkspaceJob.java:39)
at org.eclipse.core.internal.jobs.Worker.run(Worker.java:55)

I think is related the google app engine not supported to deploy project with appcfg.
they support only deploy with gcloud but my project is not maven and i do not know how to deploy project with gcloud.
I try to convert to maven project and deploy with gcloud but when I run
mvn package appengine:deploy -Dapp.deploy.projectId=myProjectId
from commandline
I get error
path to file /BaseResourceCss.java:[3,39] package com.google.gwt.resources.client does not exist
and I get like this for all files in project

thank you everyone

Since the last August 30th the appcfg is deprecated. As you can see in the shared link, it is recommended to use the gcloud commands.

Depends on the language you are using, is the command you need to execute. Below are the examples:

For Java 8 apps, build the app first. Then deploy with:

gcloud app deploy WEB-INF/appengine.xml

For Java 11 apps, you can deploy the source code to the Java 11 runtime without building locally:

gcloud app deploy pom.xml

To deploy a Java fatjar to the Java 11 runtime:

gcloud app deploy myapp.jar

You can also use the Cloud SDK-based Maven or Gradle plugins to build and deploy Java 8 and Java 11 apps.