Warnings issued from bitcoinj or otherwise should be logged for diagnostic purposes. It's likely simplest to achieve this by adding a log configuration class that is picked up by https://docs.oracle.com/javase/7/docs/api/java/util/logging/LogManager.html and puts a "warn" level log into the same directory as the wallet and SPV chain files.
Warnings issued from bitcoinj or otherwise should be logged for diagnostic purposes. It's likely simplest to achieve this by adding a log configuration class that is picked up by https://docs.oracle.com/javase/7/docs/api/java/util/logging/LogManager.html and puts a "warn" level log into the same directory as the wallet and SPV chain files.