Fix downstream failures due to new error prone checks

[hvadehra]

New error prone checks since the last java_tools release now break bazel and other downstream projects (https://buildkite.com/bazel/bazel-at-head-plus-downstream/builds/2430)
This is currently blocking a java_tools release (bazelbuild/java_tools#55).

I plan to disable the checks for now (as done before in bazelbuild/bazel@cf57345) on the default java toolchain and proceed with the release.

Filing this issue to track fixing of downstream and then re-enable the checks.

cc @comius

[cushon]

Disabling globally to make progress is OK with me.

These are the distinct errors I saw, which could be fixed more locally. Did you see others?

api/src/test/java/com/google/common/flogger/LogContextTest.java:418: error: [FloggerLogString] Arguments to log(String) must be compile-time constants or parameters annotated with @CompileTimeConstant. If possible, use Flogger's formatting log methods instead.
--
  | logger.atInfo().log(nullString);
  | ^

external/desugar_jdk_libs/src/share/classes/java/util/stream/Collectors.java:630: error: [ReturnValueIgnored] Return value of 'sumWithCompensation' must be used
--
  | (a, t) -> { sumWithCompensation(a, mapper.applyAsDouble(t)); a[2]++; a[3]+= mapper.applyAsDouble(t);},
  | ^

[hvadehra]

The Flogger test needs to be updated. It's been fixed internally (423382085) but for some reason has not been exported to github yet (probably waiting for an error prone release)
The latter desugar lib failure is the one I'm attempting to fix with the global disable of ReturnValueIgnored (afaict flags allowing more fine-grained disabling have been removed)
These are the only failures related to error prone.

[cushon]

The original flogger fix was made internal only, I just mailed cl/441196089

For desugar I think you could also add the flag to the javacopts for the affected target, but disabling it globally to unblock the release is still fine with me

[hvadehra]

Got it, I'll mail a change to update it locally at desugar as a followup.