error-prone: error_prone_core 2.0.6 adds Objects.requireNonNull() to source (which can crash Android)

I’ve been using the error-prone compiler for my Android application. java.util.Objects was only added recently to Android (API 19). The most recent version of error_prone_core (2.0.6) can add Objects.requireNonNull() to the source, which causes the Android app to crash if run on an older device.

I haven’t been able to track down exactly how this happens; I’m not super familiar with error-prone’s internals.

I’ve been using error-prone via the gradle-errorprone-plugin for Android builds. By default it pulls in the latest error_prone_core for use. As a workaround you can force it to use 2.0.5.

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As an aside, the stack traces that result are quite mystifying since the source will contain no references to java.util.Objects. For example:

Fatal Exception: java.lang.NoClassDefFoundError: java.util.Objects
       at com.trello.syncadapter.StarredBoardsSync.execute(StarredBoardsSync.java:66)
       at com.trello.syncadapter.StarredBoardsSync.performSync(StarredBoardsSync.java:58)
       at com.trello.syncadapter.TSyncAdapter.onPerformSync(TSyncAdapter.java:49)
       at android.content.AbstractThreadedSyncAdapter$SyncThread.run(AbstractThreadedSyncAdapter.java:254)

…Where StarredBoardsSync didn’t even import java.util.Objects in the original source.