com.google.cloud.spanner.SpannerException: 
DEADLINE_EXCEEDED: Operation failed 20 times because of other pending operations. Giving up operation.
at com.google.cloud.spanner.SpannerExceptionFactory.newSpannerExceptionPreformatted(SpannerExceptionFactory.java:284)
at com.google.cloud.spanner.SpannerExceptionFactory.newSpannerException(SpannerExceptionFactory.java:61)
at [email protected]/com.example.spanner.SpannerSampleIT$ShouldRetryBackupOperation.test(SpannerSampleIT.java:502)
at [email protected]/com.example.spanner.SpannerSampleIT$ShouldRetryBackupOperation.test(SpannerSampleIT.java:491)
at [email protected]/com.example.spanner.SampleRunner.runSampleWithRetry(SampleRunner.java:47)
at [email protected]/com.example.spanner.SpannerSampleIT.testSample(SpannerSampleIT.java:427)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:566)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:59)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:56)
at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
at org.junit.runners.ParentRunner$3.evaluate(ParentRunner.java:306)
at org.junit.runners.BlockJUnit4ClassRunner$1.evaluate(BlockJUnit4ClassRunner.java:100)
at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:366)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:103)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:63)
at org.junit.runners.ParentRunner$4.run(ParentRunner.java:331)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:79)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:329)
at org.junit.runners.ParentRunner.access$100(ParentRunner.java:66)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:293)
at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26)
at org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:27)
at org.junit.runners.ParentRunner$3.evaluate(ParentRunner.java:306)
at org.junit.runners.ParentRunner.run(ParentRunner.java:413)
at org.apache.maven.surefire.junit4.JUnit4Provider.execute(JUnit4Provider.java:364)
at org.apache.maven.surefire.junit4.JUnit4Provider.executeWithRerun(JUnit4Provider.java:272)
at org.apache.maven.surefire.junit4.JUnit4Provider.executeTestSet(JUnit4Provider.java:237)
at org.apache.maven.surefire.junit4.JUnit4Provider.invoke(JUnit4Provider.java:158)
at org.apache.maven.surefire.booter.ForkedBooter.runSuitesInProcess(ForkedBooter.java:428)
at org.apache.maven.surefire.booter.ForkedBooter.execute(ForkedBooter.java:162)
at org.apache.maven.surefire.booter.ForkedBooter.run(ForkedBooter.java:562)
at org.apache.maven.surefire.booter.ForkedBooter.main(ForkedBooter.java:548)

Caused by: com.google.cloud.spanner.SpannerException: FAILED_PRECONDITION: io.grpc.StatusRuntimeException: FAILED_PRECONDITION: Cannot restore database (projects/gcloud-devel/instances/spanner-testing/databases/mysample-3f681233-538b-4338-a) because the maximum number of pending restores (1) for the instance (projects/gcloud-devel/instances/spanner-testing) has been reached. Please retry the operation once the pending restores complete.

at com.google.cloud.spanner.SpannerExceptionFactory.newSpannerExceptionPreformatted(SpannerExceptionFactory.java:284)

at com.google.cloud.spanner.SpannerExceptionFactory.newSpannerException(SpannerExceptionFactory.java:61)

at com.google.cloud.spanner.SpannerExceptionFactory.fromApiException(SpannerExceptionFactory.java:299)

at com.google.cloud.spanner.SpannerExceptionFactory.newSpannerException(SpannerExceptionFactory.java:174)

at com.google.cloud.spanner.SpannerExceptionFactory.newSpannerException(SpannerExceptionFactory.java:110)

at com.google.cloud.spanner.DatabaseAdminClientImpl.lambda$restoreDatabase$1(DatabaseAdminClientImpl.java:117)

at com.google.api.core.ApiFutures$ApiFunctionToGuavaFunction.apply(ApiFutures.java:240)

at com.google.common.util.concurrent.AbstractCatchingFuture$CatchingFuture.doFallback(AbstractCatchingFuture.java:224)

at com.google.common.util.concurrent.AbstractCatchingFuture$CatchingFuture.doFallback(AbstractCatchingFuture.java:212)

at com.google.common.util.concurrent.AbstractCatchingFuture.run(AbstractCatchingFuture.java:124)

at com.google.common.util.concurrent.DirectExecutor.execute(DirectExecutor.java:30)

at com.google.common.util.concurrent.AbstractFuture.executeListener(AbstractFuture.java:1215)

at com.google.common.util.concurrent.AbstractFuture.addListener(AbstractFuture.java:724)

at com.google.common.util.concurrent.FluentFuture$TrustedFuture.addListener(FluentFuture.java:108)

at com.google.common.util.concurrent.ForwardingListenableFuture.addListener(ForwardingListenableFuture.java:45)

at com.google.api.core.ApiFutureToListenableFuture.addListener(ApiFutureToListenableFuture.java:52)

at com.google.common.util.concurrent.AbstractCatchingFuture.create(AbstractCatchingFuture.java:41)

at com.google.common.util.concurrent.Futures.catching(Futures.java:282)

at com.google.api.core.ApiFutures.catching(ApiFutures.java:99)

at com.google.api.gax.longrunning.OperationFutureImpl.(OperationFutureImpl.java:97)

at com.google.cloud.spanner.DatabaseAdminClientImpl.restoreDatabase(DatabaseAdminClientImpl.java:115)

at [email protected]/com.example.spanner.RestoreBackupWithEncryptionKey.restoreBackupWithEncryptionKey(RestoreBackupWithEncryptionKey.java:67)

at [email protected]/com.example.spanner.SpannerSampleIT.lambda$testSample$2(SpannerSampleIT.java:428)

at [email protected]/com.example.spanner.SampleRunner.runSampleWithRetry(SampleRunner.java:44)

... 31 more

Caused by: io.grpc.StatusRuntimeException: FAILED_PRECONDITION: Cannot restore database (projects/gcloud-devel/instances/spanner-testing/databases/mysample-3f681233-538b-4338-a) because the maximum number of pending restores (1) for the instance (projects/gcloud-devel/instances/spanner-testing) has been reached. Please retry the operation once the pending restores complete.

at io.grpc.Status.asRuntimeException(Status.java:535)

at io.grpc.stub.ClientCalls$UnaryStreamToFuture.onClose(ClientCalls.java:533)

at io.grpc.PartialForwardingClientCallListener.onClose(PartialForwardingClientCallListener.java:39)

at io.grpc.ForwardingClientCallListener.onClose(ForwardingClientCallListener.java:23)

at io.grpc.ForwardingClientCallListener$SimpleForwardingClientCallListener.onClose(ForwardingClientCallListener.java:40)

at com.google.cloud.spanner.spi.v1.SpannerErrorInterceptor$1$1.onClose(SpannerErrorInterceptor.java:100)

at io.grpc.internal.ClientCallImpl.closeObserver(ClientCallImpl.java:553)

at io.grpc.internal.ClientCallImpl.access$300(ClientCallImpl.java:68)

at io.grpc.internal.ClientCallImpl$ClientStreamListenerImpl$1StreamClosed.runInternal(ClientCallImpl.java:739)

at io.grpc.internal.ClientCallImpl$ClientStreamListenerImpl$1StreamClosed.runInContext(ClientCallImpl.java:718)

at io.grpc.internal.ContextRunnable.run(ContextRunnable.java:37)

at io.grpc.internal.SerializingExecutor.run(SerializingExecutor.java:123)

at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:515)

at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)

at java.base/java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:304)

at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)

at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)

at java.base/java.lang.Thread.run(Thread.java:829)