"Needed to have 6 in buffer but only had 0"

In the HR test suite I had to disable a test, as seen here:

https://github.com/hibernate/hibernate-reactive/blob/2ff95a963d18c863853f6258490d4ace341eb00c/hibernate-reactive-core/src/test/java/org/hibernate/reactive/OrderedEmbeddableCollectionTest.java#L32

because of an intermittent error that only occurred on DB2 when running the whole test suite (and not the single test).

From the error message it looks like this is something y'all know about already.

```
ERROR errors [vert.x-eventloop-thread-0] failed to execute statement [select orderedemb0_.id as id1_0_0_, orderedemb0_.title as title2_0_0_ from EAuthor orderedemb0_ where orderedemb0_.id=?]
ERROR errors [vert.x-eventloop-thread-0] could not load an entity: [org.hibernate.reactive.OrderedEmbeddableCollectionTest$Author#1]
java.util.concurrent.CompletionException: java.lang.IllegalStateException: Needed to have 6 in buffer but only had 0. In JDBC we would normally block here but need to find a non-blocking solution
at java.util.concurrent.CompletableFuture.encodeThrowable(CompletableFuture.java:331) ~[?:?]
at java.util.concurrent.CompletableFuture.completeThrowable(CompletableFuture.java:346) ~[?:?]
at java.util.concurrent.CompletableFuture$UniApply.tryFire(CompletableFuture.java:632) ~[?:?]
at java.util.concurrent.CompletableFuture.postComplete(CompletableFuture.java:506) ~[?:?]
at java.util.concurrent.CompletableFuture.completeExceptionally(CompletableFuture.java:2088) ~[?:?]
at org.hibernate.reactive.pool.impl.Handlers.lambda$toCompletionStage$0(Handlers.java:29) ~[main/:?]
at io.vertx.sqlclient.impl.SqlResultHandler.fail(SqlResultHandler.java:103) ~[vertx-sql-client-3.9.5.jar:3.9.5]
at io.vertx.sqlclient.impl.SqlResultHandler.handle(SqlResultHandler.java:89) ~[vertx-sql-client-3.9.5.jar:3.9.5]
at io.vertx.sqlclient.impl.SqlResultHandler.handle(SqlResultHandler.java:33) ~[vertx-sql-client-3.9.5.jar:3.9.5]
at io.vertx.sqlclient.impl.TransactionImpl.lambda$null$3(TransactionImpl.java:181) ~[vertx-sql-client-3.9.5.jar:3.9.5]
at io.vertx.sqlclient.impl.TransactionImpl.lambda$rollback$2(TransactionImpl.java:140) ~[vertx-sql-client-3.9.5.jar:3.9.5]
at io.vertx.sqlclient.impl.SocketConnectionBase.handleMessage(SocketConnectionBase.java:241) ~[vertx-sql-client-3.9.5.jar:3.9.5]
at io.vertx.sqlclient.impl.SocketConnectionBase.lambda$init$0(SocketConnectionBase.java:88) ~[vertx-sql-client-3.9.5.jar:3.9.5]
at io.vertx.core.net.impl.NetSocketImpl.lambda$new$2(NetSocketImpl.java:101) ~[vertx-core-3.9.5.jar:3.9.5]
at io.vertx.core.streams.impl.InboundBuffer.handleEvent(InboundBuffer.java:237) ~[vertx-core-3.9.5.jar:3.9.5]
at io.vertx.core.streams.impl.InboundBuffer.write(InboundBuffer.java:127) ~[vertx-core-3.9.5.jar:3.9.5]
at io.vertx.core.net.impl.NetSocketImpl.handleMessage(NetSocketImpl.java:357) ~[vertx-core-3.9.5.jar:3.9.5]
at io.vertx.core.impl.ContextImpl.executeTask(ContextImpl.java:366) ~[vertx-core-3.9.5.jar:3.9.5]
at io.vertx.core.impl.EventLoopContext.execute(EventLoopContext.java:43) ~[vertx-core-3.9.5.jar:3.9.5]
at io.vertx.core.impl.ContextImpl.executeFromIO(ContextImpl.java:229) ~[vertx-core-3.9.5.jar:3.9.5]
at io.vertx.core.net.impl.VertxHandler.channelRead(VertxHandler.java:163) ~[vertx-core-3.9.5.jar:3.9.5]
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379) ~[netty-transport-4.1.49.Final.jar:4.1.49.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365) ~[netty-transport-4.1.49.Final.jar:4.1.49.Final]
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:357) ~[netty-transport-4.1.49.Final.jar:4.1.49.Final]
at io.netty.channel.CombinedChannelDuplexHandler$DelegatingChannelHandlerContext.fireChannelRead(CombinedChannelDuplexHandler.java:436) ~[netty-transport-4.1.49.Final.jar:4.1.49.Final]
at io.vertx.db2client.impl.codec.DB2Encoder.lambda$write$0(DB2Encoder.java:72) ~[vertx-db2-client-3.9.5.jar:3.9.5]
at io.vertx.db2client.impl.codec.DB2Decoder.decodePayload(DB2Decoder.java:97) [vertx-db2-client-3.9.5.jar:3.9.5]
at io.vertx.db2client.impl.codec.DB2Decoder.decode(DB2Decoder.java:53) [vertx-db2-client-3.9.5.jar:3.9.5]
at io.netty.handler.codec.ByteToMessageDecoder.decodeRemovalReentryProtection(ByteToMessageDecoder.java:501) [netty-codec-4.1.49.Final.jar:4.1.49.Final]
at io.netty.handler.codec.ByteToMessageDecoder.callDecode(ByteToMessageDecoder.java:440) [netty-codec-4.1.49.Final.jar:4.1.49.Final]
at io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:276) [netty-codec-4.1.49.Final.jar:4.1.49.Final]
at io.netty.channel.CombinedChannelDuplexHandler.channelRead(CombinedChannelDuplexHandler.java:251) [netty-transport-4.1.49.Final.jar:4.1.49.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379) [netty-transport-4.1.49.Final.jar:4.1.49.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365) [netty-transport-4.1.49.Final.jar:4.1.49.Final]
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:357) [netty-transport-4.1.49.Final.jar:4.1.49.Final]
at io.netty.channel.DefaultChannelPipeline$HeadContext.channelRead(DefaultChannelPipeline.java:1410) [netty-transport-4.1.49.Final.jar:4.1.49.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379) [netty-transport-4.1.49.Final.jar:4.1.49.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365) [netty-transport-4.1.49.Final.jar:4.1.49.Final]
at io.netty.channel.DefaultChannelPipeline.fireChannelRead(DefaultChannelPipeline.java:919) [netty-transport-4.1.49.Final.jar:4.1.49.Final]
at io.netty.channel.nio.AbstractNioByteChannel$NioByteUnsafe.read(AbstractNioByteChannel.java:163) [netty-transport-4.1.49.Final.jar:4.1.49.Final]
at io.netty.channel.nio.NioEventLoop.processSelectedKey(NioEventLoop.java:714) [netty-transport-4.1.49.Final.jar:4.1.49.Final]
at io.netty.channel.nio.NioEventLoop.processSelectedKeysOptimized(NioEventLoop.java:650) [netty-transport-4.1.49.Final.jar:4.1.49.Final]
at io.netty.channel.nio.NioEventLoop.processSelectedKeys(NioEventLoop.java:576) [netty-transport-4.1.49.Final.jar:4.1.49.Final]
at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:493) [netty-transport-4.1.49.Final.jar:4.1.49.Final]
at io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:989) [netty-common-4.1.49.Final.jar:4.1.49.Final]
at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74) [netty-common-4.1.49.Final.jar:4.1.49.Final]
at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30) [netty-common-4.1.49.Final.jar:4.1.49.Final]
at java.lang.Thread.run(Thread.java:834) [?:?]
Caused by: java.lang.IllegalStateException: Needed to have 6 in buffer but only had 0. In JDBC we would normally block here but need to find a non-blocking solution
at io.vertx.db2client.impl.drda.DRDAResponse.ensureALayerDataInBuffer(DRDAResponse.java:1462) ~[vertx-db2-client-3.9.5.jar:3.9.5]
at io.vertx.db2client.impl.drda.DRDAResponse.readDssHeader(DRDAResponse.java:878) ~[vertx-db2-client-3.9.5.jar:3.9.5]
at io.vertx.db2client.impl.drda.DRDAResponse.startSameIdChainParse(DRDAResponse.java:52) ~[vertx-db2-client-3.9.5.jar:3.9.5]
at io.vertx.db2client.impl.drda.DRDAQueryResponse.readDescribeInput(DRDAQueryResponse.java:81) ~[vertx-db2-client-3.9.5.jar:3.9.5]
at io.vertx.db2client.impl.drda.DRDAQueryResponse.readPrepareDescribeInputOutput(DRDAQueryResponse.java:53) ~[vertx-db2-client-3.9.5.jar:3.9.5]
at io.vertx.db2client.impl.codec.PrepareStatementCodec.decodePayload(PrepareStatementCodec.java:76) ~[vertx-db2-client-3.9.5.jar:3.9.5]
at io.vertx.db2client.impl.codec.DB2Decoder.decodePayload(DB2Decoder.java:80) ~[vertx-db2-client-3.9.5.jar:3.9.5]
... 21 more
```