Unsupported vault setting found in JSON: useIpv6

When I try to build the cryptomator with eclipse Mars 2 in Ubuntu, the flowing warnings are appear in console logs, and failed to build:

[main] WARN org.cryptomator.common.settings.SettingsJsonAdapter - Unsupported vault setting found in JSON: useIpv6 [main] WARN org.cryptomator.common.settings.VaultSettingsJsonAdapter - Unsupported vault setting found in JSON: shouldBeIgnored

how can I fix it?

Answered in https://github.com/cryptomator/cryptomator/issues/582#issuecomment-330496065