project.toml (7 lines of code) (raw):
# Default version is Java 11
# - See https://cloud.google.com/docs/buildpacks/java#specify_a_java_version
# Match the version required in pom.xml by setting it here
# - See https://cloud.google.com/docs/buildpacks/set-environment-variables#build_the_application_with_environment_variables
[[build.env]]
name = "GOOGLE_RUNTIME_VERSION"
value = "17"