Cannot deploy Java WAR application without app.yml file on GAE

I have a SpringBoot Application ant it's deployed on Google App Engine, I deployed it many times before (158) using google cloud maven plugin, but today without any changes on my core nor deployment rules I got the next error message:

INFO: submitting command: /root/.cache/google-cloud-tools-java/managed-cloud-sdk/LATEST/google-cloud-sdk/bin/gcloud app deploy --promote --version 1 --project <my-project-name> --credential-file-override /app/keys/<my-key>.json
GCLOUD: ERROR: (gcloud.app.deploy) Failed to parse YAML from [gs://runtime-builder/experiments.yaml]: mapping values are not allowed here
GCLOUD:   in "<file>", line 2, column 14

In my project I have no yml configurations, as it's java I just have appengine-web.xml configuration.

Any idea about this??

Thanks in advance

Update: I'm using the appengine-maven-plugin, and I have the next configuration:

<plugin>
  <groupId>com.google.cloud.tools</groupId>
  <artifactId>appengine-maven-plugin</artifactId>
  <version>2.2.0</version>
  <configuration>
    <version>${app.target.version}</version>
    <promote>${app.promote.version}</promote>
    <projectId>${gae.app.name}</projectId>
    <serviceAccountKeyFile>${gae.key.location}</serviceAccountKeyFile>
  </configuration>
</plugin>

[SOLUTION] 1. Downgrade plugin version 2. Set older gCloud SDK

Final configuration:

<plugin>
    <groupId>com.google.cloud.tools</groupId>
    <artifactId>appengine-maven-plugin</artifactId>
    <version>2.0.0-rc5</version> <!-- Downgraded -->
    <configuration>
      <version>${app.target.version}</version>
      <promote>${app.promote.version}</promote>
      <projectId>${gae.app.name}</projectId>
      <serviceAccountKeyFile>${gae.key.location}</serviceAccountKeyFile>
      <cloudSdkVersion>271.0.0</cloudSdkVersion> <!-- Set older sdk version -->
    </configuration>
  </plugin>

Possible duplicate of: Can't deploy to app engine standard with gcloud components 272.0.0

You can try this:

Having the same issue here. As of now, the only way is to revert to an older version.

gcloud components update --version=271.0.0

As of 1.55PM(PDT), it seems to be fixed on the latest version. You can update to the latest again!