[BUG] Registering transport action fails for extension

[owaiskazi19]

What is the bug?

org.opensearch.transport.RemoteTransportException: [runTask-0][127.0.0.1:9300][internal:discovery/registertransportactions]
Caused by: java.lang.IllegalArgumentException: Could not read transport action
        at org.opensearch.extensions.RegisterTransportActionsRequest.<init>(RegisterTransportActionsRequest.java:54) ~[opensearch-3.0.0-SNAPSHOT.jar:3.0.0-SNAPSHOT]
        at org.opensearch.transport.RequestHandlerRegistry.newRequest(RequestHandlerRegistry.java:85) ~[opensearch-3.0.0-SNAPSHOT.jar:3.0.0-SNAPSHOT]
        at org.opensearch.transport.InboundHandler.newRequest(InboundHandler.java:282) ~[opensearch-3.0.0-SNAPSHOT.jar:3.0.0-SNAPSHOT]
        at org.opensearch.transport.InboundHandler.handleRequest(InboundHandler.java:242) ~[opensearch-3.0.0-SNAPSHOT.jar:3.0.0-SNAPSHOT]
        at org.opensearch.transport.InboundHandler.messageReceived(InboundHandler.java:132) ~[opensearch-3.0.0-SNAPSHOT.jar:3.0.0-SNAPSHOT]
        at org.opensearch.transport.InboundHandler.inboundMessage(InboundHandler.java:114) ~[opensearch-3.0.0-SNAPSHOT.jar:3.0.0-SNAPSHOT]
        at org.opensearch.transport.TcpTransport.inboundMessage(TcpTransport.java:769) ~[opensearch-3.0.0-SNAPSHOT.jar:3.0.0-SNAPSHOT]
        at org.opensearch.transport.InboundPipeline.forwardFragments(InboundPipeline.java:175) ~[opensearch-3.0.0-SNAPSHOT.jar:3.0.0-SNAPSHOT]
        at org.opensearch.transport.InboundPipeline.doHandleBytes(InboundPipeline.java:150) ~[opensearch-3.0.0-SNAPSHOT.jar:3.0.0-SNAPSHOT]
        at org.opensearch.transport.InboundPipeline.handleBytes(InboundPipeline.java:115) ~[opensearch-3.0.0-SNAPSHOT.jar:3.0.0-SNAPSHOT]
        at org.opensearch.transport.netty4.Netty4MessageChannelHandler.channelRead(Netty4MessageChannelHandler.java:94) ~[transport-netty4-client-3.0.0-SNAPSHOT.jar:3.0.0-SNAPSHOT]
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:442) ~[netty-transport-4.1.89.Final.jar:4.1.89.Final]
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:420) ~[netty-transport-4.1.89.Final.jar:4.1.89.Final]
        at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:412) ~[netty-transport-4.1.89.Final.jar:4.1.89.Final]
        at io.netty.handler.logging.LoggingHandler.channelRead(LoggingHandler.java:280) ~[netty-handler-4.1.89.Final.jar:4.1.89.Final]
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:442) ~[netty-transport-4.1.89.Final.jar:4.1.89.Final]
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:420) ~[netty-transport-4.1.89.Final.jar:4.1.89.Final]
        at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:412) ~[netty-transport-4.1.89.Final.jar:4.1.89.Final]
        at io.netty.handler.codec.MessageToMessageDecoder.channelRead(MessageToMessageDecoder.java:103) ~[netty-codec-4.1.89.Final.jar:4.1.89.Final]
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:444) ~[netty-transport-4.1.89.Final.jar:4.1.89.Final]
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:420) ~[netty-transport-4.1.89.Final.jar:4.1.89.Final]
        at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:412) ~[netty-transport-4.1.89.Final.jar:4.1.89.Final]
        at io.netty.channel.DefaultChannelPipeline$HeadContext.channelRead(DefaultChannelPipeline.java:1410) ~[netty-transport-4.1.89.Final.jar:4.1.89.Final]
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:440) ~[netty-transport-4.1.89.Final.jar:4.1.89.Final]
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:420) ~[netty-transport-4.1.89.Final.jar:4.1.89.Final]
        at io.netty.channel.DefaultChannelPipeline.fireChannelRead(DefaultChannelPipeline.java:919) ~[netty-transport-4.1.89.Final.jar:4.1.89.Final]
        at io.netty.channel.nio.AbstractNioByteChannel$NioByteUnsafe.read(AbstractNioByteChannel.java:166) ~[netty-transport-4.1.89.Final.jar:4.1.89.Final]
        at io.netty.channel.nio.NioEventLoop.processSelectedKey(NioEventLoop.java:788) ~[netty-transport-4.1.89.Final.jar:4.1.89.Final]
        at io.netty.channel.nio.NioEventLoop.processSelectedKeysPlain(NioEventLoop.java:689) ~[netty-transport-4.1.89.Final.jar:4.1.89.Final]
        at io.netty.channel.nio.NioEventLoop.processSelectedKeys(NioEventLoop.java:652) ~[netty-transport-4.1.89.Final.jar:4.1.89.Final]
        at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:562) ~[netty-transport-4.1.89.Final.jar:4.1.89.Final]
        at io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:997) ~[netty-common-4.1.89.Final.jar:4.1.89.Final]
        at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74) ~[netty-common-4.1.89.Final.jar:4.1.89.Final]
        at java.lang.Thread.run(Thread.java:832) [?:?]

How can one reproduce the bug?

1. Run SDK ./gradlew helloWorld or run an extension ./gradlew run
2. Run OpenSearch ./gradlew run

What is the expected behavior?

Communication between OpenSearch and SDK should happen smoothly!

What is your host/environment?

Mac OS X

Do you have any screenshots?

If applicable, add screenshots to help explain your problem.

Do you have any additional context?

Add any other context about the problem.

[dbwiddis]

It's not finding the classes that exist in extensions (by design).