SoftIndexFileStore index update concurrency issue

<distributed-cache name="api-general-filestore-without-expiration" owners="2" segments="30" mode="SYNC" remote-timeout="25000" start="EAGER">
         <persistence passivation="true">
            <file-store max-entries="1000000" path="${infinispan.server.data.path}/api-general-filestore-without-expiration" shared="false" preload="false" fetch-state="true" purge="true"/>
         </persistence>
      </distributed-cache>

      ConfigurationBuilder builder = new ConfigurationBuilder();
      builder.addServer()
            .host("127.0.0.1");
      builder.security().authentication()
            .username("admin")
            .password("admin");
      RemoteCacheManager remoteCacheManager = new RemoteCacheManager(builder.build());

      RemoteCache remoteCache = remoteCacheManager.getCache("api-general-filestore-without-expiration");
      for (int i = 0; i < 100; i++) {
         remoteCache.put("foo-" + i, "bar-" + i);
      }

2021-06-28 11:02:41,483 INFO  (main) [org.jboss.threads] JBoss Threads version 2.3.3.Final
2021-06-28 11:02:41,566 WARN  (main) [org.infinispan.encoding.impl.StorageConfigurationManager] ISPN000599: Configuration for cache 'api-general-filestore-without-expiration' does not define the encoding for keys or values. If you use operations that require data conversion or queries, you should configure the cache with a specific MediaType for keys or values.
2021-06-28 11:02:41,880 INFO  (main) [org.infinispan.CONTAINER] ISPN000104: Using EmbeddedTransactionManager
2021-06-28 11:02:42,195 INFO  (main) [org.infinispan.server.core.RequestTracer] OpenTracing integration is disabled
2021-06-28 11:02:42,280 INFO  (ForkJoinPool.commonPool-worker-3) [org.infinispan.SERVER] ISPN080018: Started connector HotRod (internal)
2021-06-28 11:02:42,388 INFO  (main) [org.infinispan.SERVER] ISPN080018: Started connector REST (internal)
2021-06-28 11:02:42,520 INFO  (main) [org.infinispan.SERVER] ISPN080004: Connector SINGLE_PORT (default) listening on 127.0.0.1:11222
2021-06-28 11:02:42,521 INFO  (main) [org.infinispan.SERVER] ISPN080034: Server 'dlovison-mac-16194' listening on http://127.0.0.1:11222
2021-06-28 11:02:42,548 INFO  (main) [org.infinispan.SERVER] ISPN080001: Infinispan Server 13.0.0-SNAPSHOT started in 6317ms
2021-06-28 11:02:57,978 WARN  (non-blocking-thread--p2-t6) [org.infinispan.CONTAINER] ISPN000214: Unable to remove entry under WrappedByteArray{bytes=\J06\f\o\o\-\3\2... (8 bytes), hashCode=-1927385149} from cache store after activation java.lang.NullPointerException: The CompletionStage terminated with null.
	at io.reactivex.rxjava3.internal.jdk8.SingleFromCompletionStage$CompletionStageHandler.accept(SingleFromCompletionStage.java:67)
	at io.reactivex.rxjava3.internal.jdk8.SingleFromCompletionStage$CompletionStageHandler.accept(SingleFromCompletionStage.java:47)
	at io.reactivex.rxjava3.internal.jdk8.FlowableFromCompletionStage$BiConsumerAtomicReference.accept(FlowableFromCompletionStage.java:90)
	at io.reactivex.rxjava3.internal.jdk8.FlowableFromCompletionStage$BiConsumerAtomicReference.accept(FlowableFromCompletionStage.java:81)
	at java.base/java.util.concurrent.CompletableFuture.uniWhenComplete(CompletableFuture.java:859)
	at java.base/java.util.concurrent.CompletableFuture$UniWhenComplete.tryFire(CompletableFuture.java:837)
	at java.base/java.util.concurrent.CompletableFuture.postComplete(CompletableFuture.java:506)
	at java.base/java.util.concurrent.CompletableFuture.complete(CompletableFuture.java:2073)
	at org.infinispan.util.concurrent.NonBlockingManagerImpl.lambda$complete$0(NonBlockingManagerImpl.java:44)
	at io.netty.util.concurrent.AbstractEventExecutor.safeExecute(AbstractEventExecutor.java:164)
	at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:472)
	at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:500)
	at io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:989)
	at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74)
	at java.base/java.lang.Thread.run(Thread.java:834)

2021-06-28 11:02:58,065 WARN  (non-blocking-thread--p2-t7) [org.infinispan.CONTAINER] ISPN000214: Unable to remove entry under WrappedByteArray{bytes=\J06\f\o\o\-\5\7... (8 bytes), hashCode=-1927385082} from cache store after activation java.lang.NullPointerException: The CompletionStage terminated with null.
	at io.reactivex.rxjava3.internal.jdk8.SingleFromCompletionStage$CompletionStageHandler.accept(SingleFromCompletionStage.java:67)
	at io.reactivex.rxjava3.internal.jdk8.SingleFromCompletionStage$CompletionStageHandler.accept(SingleFromCompletionStage.java:47)
	at io.reactivex.rxjava3.internal.jdk8.FlowableFromCompletionStage$BiConsumerAtomicReference.accept(FlowableFromCompletionStage.java:90)
	at io.reactivex.rxjava3.internal.jdk8.FlowableFromCompletionStage$BiConsumerAtomicReference.accept(FlowableFromCompletionStage.java:81)
	at java.base/java.util.concurrent.CompletableFuture.uniWhenComplete(CompletableFuture.java:859)
	at java.base/java.util.concurrent.CompletableFuture$UniWhenComplete.tryFire(CompletableFuture.java:837)
	at java.base/java.util.concurrent.CompletableFuture.postComplete(CompletableFuture.java:506)
	at java.base/java.util.concurrent.CompletableFuture.complete(CompletableFuture.java:2073)
	at org.infinispan.util.concurrent.NonBlockingManagerImpl.lambda$complete$0(NonBlockingManagerImpl.java:44)
	at io.netty.util.concurrent.AbstractEventExecutor.safeExecute(AbstractEventExecutor.java:164)
	at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:472)
	at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:500)
	at io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:989)
	at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74)
	at java.base/java.lang.Thread.run(Thread.java:834)

2021-06-28 11:02:58,111 WARN  (non-blocking-thread--p2-t7) [org.infinispan.CONTAINER] ISPN000214: Unable to remove entry under WrappedByteArray{bytes=\J06\f\o\o\-\7\3... (8 bytes), hashCode=-1927385024} from cache store after activation java.lang.NullPointerException: The CompletionStage terminated with null.
	at io.reactivex.rxjava3.internal.jdk8.SingleFromCompletionStage$CompletionStageHandler.accept(SingleFromCompletionStage.java:67)
	at io.reactivex.rxjava3.internal.jdk8.SingleFromCompletionStage$CompletionStageHandler.accept(SingleFromCompletionStage.java:47)
	at io.reactivex.rxjava3.internal.jdk8.FlowableFromCompletionStage$BiConsumerAtomicReference.accept(FlowableFromCompletionStage.java:90)
	at io.reactivex.rxjava3.internal.jdk8.FlowableFromCompletionStage$BiConsumerAtomicReference.accept(FlowableFromCompletionStage.java:81)
	at java.base/java.util.concurrent.CompletableFuture.uniWhenComplete(CompletableFuture.java:859)
	at java.base/java.util.concurrent.CompletableFuture$UniWhenComplete.tryFire(CompletableFuture.java:837)
	at java.base/java.util.concurrent.CompletableFuture.postComplete(CompletableFuture.java:506)
	at java.base/java.util.concurrent.CompletableFuture.complete(CompletableFuture.java:2073)
	at org.infinispan.util.concurrent.NonBlockingManagerImpl.lambda$complete$0(NonBlockingManagerImpl.java:44)
	at io.netty.util.concurrent.AbstractEventExecutor.safeExecute(AbstractEventExecutor.java:164)
	at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:472)
	at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:500)
	at io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:989)
	at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74)
	at java.base/java.lang.Thread.run(Thread.java:834)

2021-06-28 11:02:58,152 WARN  (non-blocking-thread--p2-t7) [org.infinispan.CONTAINER] ISPN000214: Unable to remove entry under WrappedByteArray{bytes=\J06\f\o\o\-\8\8... (8 bytes), hashCode=-1927384988} from cache store after activation java.lang.NullPointerException: The CompletionStage terminated with null.
	at io.reactivex.rxjava3.internal.jdk8.SingleFromCompletionStage$CompletionStageHandler.accept(SingleFromCompletionStage.java:67)
	at io.reactivex.rxjava3.internal.jdk8.SingleFromCompletionStage$CompletionStageHandler.accept(SingleFromCompletionStage.java:47)
	at io.reactivex.rxjava3.internal.jdk8.FlowableFromCompletionStage$BiConsumerAtomicReference.accept(FlowableFromCompletionStage.java:90)
	at io.reactivex.rxjava3.internal.jdk8.FlowableFromCompletionStage$BiConsumerAtomicReference.accept(FlowableFromCompletionStage.java:81)
	at java.base/java.util.concurrent.CompletableFuture.uniWhenComplete(CompletableFuture.java:859)
	at java.base/java.util.concurrent.CompletableFuture$UniWhenComplete.tryFire(CompletableFuture.java:837)
	at java.base/java.util.concurrent.CompletableFuture.postComplete(CompletableFuture.java:506)
	at java.base/java.util.concurrent.CompletableFuture.complete(CompletableFuture.java:2073)
	at org.infinispan.util.concurrent.NonBlockingManagerImpl.lambda$complete$0(NonBlockingManagerImpl.java:44)
	at io.netty.util.concurrent.AbstractEventExecutor.safeExecute(AbstractEventExecutor.java:164)
	at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:472)
	at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:500)
	at io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:989)
	at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74)
	at java.base/java.lang.Thread.run(Thread.java:834)