Make DeterministicRunner#close always block until the closing is done (#1255)

Author: Spikhalskiy

temporal-sdk/src/main/java/io/temporal/internal/replay/WorkflowExecutorCache.java

@@ -37,9 +37,11 @@
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.locks.Lock;
 import java.util.concurrent.locks.ReentrantLock;
+import javax.annotation.concurrent.ThreadSafe;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
+@ThreadSafe
 public final class WorkflowExecutorCache {
   private final Logger log = LoggerFactory.getLogger(WorkflowExecutorCache.class);
 

temporal-sdk/src/main/java/io/temporal/internal/sync/DeterministicRunner.java

@@ -79,21 +79,13 @@ static DeterministicRunner newRunner(
   /** IsDone returns true when all of threads are completed */
   boolean isDone();
 
-  /**
-   * @return exit value passed to {@link WorkflowThread#exit(Object)}
-   */
-  Object getExitValue();
-
   /**
    * Request cancellation of the computation. Calls {@link CancellationScope#cancel(String)} on the
    * root scope that wraps the root Runnable.
    */
   void cancel(String reason);
 
-  /**
-   * Destroys all threads by throwing {@link DestroyWorkflowThreadError} without waiting for their
-   * completion
-   */
+  /** Destroys all controlled workflow threads, blocks until the threads are destroyed */
   void close();
 
   /** Stack trace of all threads owned by the DeterministicRunner instance */