Classes that use OnComplete introduced with Akka 2.0-M4 are flagged with this error in Eclipse IDE:

Duplicate methods named andThen with the parameters (Function1) and (Function1<BoxedUnit,C>) are defined by the type japi.CallbackBridge<Either<Throwable,Integer>>

SBT compiles and runs the code fine, however Eclipse IDE refuses to run the code. Here is a sample class:

import java.util.concurrent.Callable;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

import akka.dispatch.ExecutionContext;
import akka.dispatch.Future;
import akka.dispatch.Futures;
import akka.dispatch.OnComplete;
import akka.japi.Procedure2;

class ApplyNonBlocking {
    private final ExecutorService executorService = Executors.newFixedThreadPool(10);

    private final ExecutionContext context = new ExecutionContext() {
        @Override public void execute(Runnable r) { executorService.execute(r); }
    };

    private final OnComplete<Integer> completionFunction = new OnComplete<Integer>() {
        
        @Override public void onComplete(Throwable exception, Integer result) {
            if (result != null) {
                System.out.println("Nonblocking Java apply result: " + result);
            } else {
                System.out.println("Nonblocking Java apply exception: " + exception);
            }
            executorService.shutdown(); // terminates program
        }
    };

    private final Callable<Integer> callable = new Callable<Integer>() {
        @Override public Integer call() {
            return 2 + 3;
        }
    };


    public void doit() {
        Future<Integer> resultFuture = Futures.future(callable, context);
        resultFuture.onComplete(completionFunction);
    }

    public static void main(String[] args) {
        new ApplyNonBlocking().doit();
    }
}

Here is build.sbt:

resolvers ++= Seq(
  "Typesafe Snapshots"    at "http://repo.typesafe.com/typesafe/snapshots",
  "Typesafe Releases"     at "http://repo.typesafe.com/typesafe/releases",
  "Scala-Tools Snapshots" at "http://scala-tools.org/repo-snapshots",
  "Scala Tools Releases"  at "http://scala-tools.org/repo-releases"
)

libraryDependencies ++= Seq(
  "org.scalatest"                 %% "scalatest"     % "1.6.1"        % "test" withSources(),
  "com.typesafe.akka"             %  "akka-actor"    % "latest.integration" withSources(),
  "org.scala-tools"               %% "scala-stm"     % "0.5-SNAPSHOT" withSources()
)