See build.gradle line 717
It is wrong:
if (CONF != "Release" && CONF != "Debug") logger.warn("Unknown configuration CONF='$CONF'. Treating as 'Release'")

it should be
if (CONF != "Release" && CONF != "Debug" && CONF != "DebugNative") logger.warn("Unknown configuration CONF='$CONF'. Treating as 'Release'")

Otherwise this warning happens (when -PCONF="DebugNative")

Unknown configuration CONF='DebugNative'. Treating as 'Release'