gradlew test failure "Could not resolve all files"

[axelrose]

Dears,

I tried to testing procedure from "devGuide.md"

./gradlew :tests:test -Dhealth_url=http://10.157.2.247/health -Dhost=10.157.2.247 -Dport=80

This fails unexpectedly with a message about unresolvable files:

> Configure project :
The Task.leftShift(Closure) method has been deprecated and is scheduled to be removed in Gradle 5.0. Please use Task.doLast(Action) instead.
        at docker_ao3cve1014n0dvowpxmanhrpa.run(/Users/ar/work/incubator-openwhisk-package-kafka/gradle/docker.gradle:60)


FAILURE: Build failed with an exception.

* What went wrong:
Could not resolve all files for configuration ':tests:testCompileClasspath'.
> Could not find org.apache.openwhisk:openwhisk-tests:1.0.0-SNAPSHOT.
  Searched in the following locations:
      https://repo1.maven.org/maven2/org/apache/openwhisk/openwhisk-tests/1.0.0-SNAPSHOT/maven-metadata.xml
      https://repo1.maven.org/maven2/org/apache/openwhisk/openwhisk-tests/1.0.0-SNAPSHOT/openwhisk-tests-1.0.0-SNAPSHOT.pom
      https://repo1.maven.org/maven2/org/apache/openwhisk/openwhisk-tests/1.0.0-SNAPSHOT/openwhisk-tests-1.0.0-SNAPSHOT-tests.jar
      file:/home/incubator-openwhisk-package-kafka/tests/libs/openwhisk-tests-1.0.0-SNAPSHOT-tests.jar
      file:/home/incubator-openwhisk-package-kafka/tests/libs/openwhisk-tests-tests.jar
      file:/home/.m2/repository/org/apache/openwhisk/openwhisk-tests/1.0.0-SNAPSHOT/maven-metadata.xml
      file:/home/.m2/repository/org/apache/openwhisk/openwhisk-tests/1.0.0-SNAPSHOT/openwhisk-tests-1.0.0-SNAPSHOT.pom
      file:/home/.m2/repository/org/apache/openwhisk/openwhisk-tests/1.0.0-SNAPSHOT/openwhisk-tests-1.0.0-SNAPSHOT-tests.jar
  Required by:
      project :tests

* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output.

* Get more help at https://help.gradle.org

BUILD FAILED in 1s
1 actionable task: 1 executed

Any ideas?
Thanks in advance,
Axel.