### Description

The `sendRequest` method is asynchronous and notifies a 
`TransportResponseHandler` when it completes the excecution
(successfully or unsuccessfully). 

When opening the connection we only catch `NodeNotConnectedException`
( https://github.com/elastic/elasticsearch/blob/main/server/src/main/java/org/elasticsearch/transport/TransportService.java#L719 ) which is currently fine as no implementations
throw other type of exception however, it'd be best to catch `Exception` here
so the `handler` gets notified of potential exceptions (as opposed to the caller
having to `try/catch` the call to `sendRequest`)
test/framework/src/main/java/org/elasticsearch/transport/AbstractSimpleTransportTestCase.java
}
                @Override
                public void handleException(TransportException exp) {
                    logger.error("Unexpected failure", exp);
                    fail("got exception instead of a response: " + exp.getMessage());
                }
            }
        ).get();
        assertThat(version0Response.value1, equalTo(1));
    }
    public void testVersionFrom1to0() throws Exception {
        serviceA.registerRequestHandler("internal:version", ThreadPool.Names.SAME, Version0Request::new, (request, channel, task) -> {
            assertThat(request.value1, equalTo(1));
            Version0Response response = new Version0Response(1);
            channel.sendResponse(response);
            assertEquals(version0, channel.getVersion());
        });
        Version1Request version1Request = new Version1Request();
        version1Request.value1 = 1;
        version1Request.value2 = 2;
        Version1Response version1Response = submitRequest(
            serviceB,
            nodeA,
            "internal:version",
            version1Request,
            new TransportResponseHandler<Version1Response>() {
                @Override
                public Version1Response read(StreamInput in) throws IOException {
                    return new Version1Response(in);
                }