spring boot application to test with travis and de

Question

Recently I ran my Spring Boot code into the Google Cloud platform. Now I want to introduce TRAVIS CI to my source code but I cant deploy it on Google Cloud because I receive the following error:

    Step #0: Pulling image: gcr.io/gcp-runtimes/java/runtime-builder@sha256:abe30c228acd8514d83430452b5a45eedea568b55d02d4ddaa2a374b1b086dd8
    Step #0: sha256:abe30c228acd8514d83430452b5a45eedea568b55d02d4ddaa2a374b1b086dd8: Pulling from gcp-runtimes/java/runtime-builder
    Step #0: Digest: sha256:abe30c228acd8514d83430452b5a45eedea568b55d02d4ddaa2a374b1b086dd8
    Step #0: Status: Downloaded newer image for gcr.io/gcp-runtimes/java/runtime-builder@sha256:abe30c228acd8514d83430452b5a45eedea568b55d02d4ddaa2a374b1b086dd8
    Step #0: Exception in thread "main" com.google.cloud.runtimes.builder.exception.ArtifactNotFoundException: No deployable artifacts were found. Unable to proceed.
    Step #0:    at com.google.cloud.runtimes.builder.buildsteps.PrebuiltRuntimeImageBuildStep.getArtifact(PrebuiltRuntimeImageBuildStep.java:77)
    Step #0:    at com.google.cloud.runtimes.builder.buildsteps.RuntimeImageBuildStep.run(RuntimeImageBuildStep.java:50)
    Step #0:    at com.google.cloud.runtimes.builder.BuildPipelineConfigurator.generateDockerResources(BuildPipelineConfigurator.java:104)
    Step #0:    at com.google.cloud.runtimes.builder.Application.main(Application.java:147)

I have configured files like:

• web.xml for using jetty
• appengine-web.xml for using the Google cloud
• .travis.yml for using Travis
• app.yaml for using Google cloud

Am I missing some files?