Make sure to use an updated JDK version (Java 11 at least) and retry the operation:
JAVA_HOME=C:\Program Files\Java\jdk-11.0.13
Another option is to directly compile the Flexible Client without the dependencies
gradlew FlexibleClient:assembleRelease FlexibleClient:publishDebugPublicationToLocalRepository
Error message
FAILURE: Build failed with an exception.
* What went wrong:
Execution failed for task ':MapboxLib:generateReleaseRFile'.
> Could not resolve all files for configuration ':MapboxLib:releaseCompileClasspath'.
> Could not find com.mapbox.mapboxsdk:mapbox-android-sdk:9.5.0.
Required by:
project :MapboxLib
....
Cause
This error appears because some modules (Mapbox) require private repository credentials to download the corresponding artifacts.
Workaround
Compile the required modules instead of the complete Flexible client. This can be done through this command:
gradlew :FlexibleClient:publishDebugPublicationToLocalRepository
Solution
As of GeneXus 17 upgrade 7, the Mapbox module is conditional to buildAll flag.