Unable to disable chunking on camel-http4 producer endpoint

It is not possible to disable chunking on camel-http4 producer endpoint. Here is a simple camel route:

<route>
    <from uri="timer://test?delay=2s&amp;repeatCount=1"/>
    <process ref="setStreamToBodyProcessor"/>
    <to uri="http4://localhost:8001/rest/test?bridgeEndpoint=true&amp;throwExceptionOnFailure=false&amp;chunked=false"/>
</route>

I am not only set option "chunked=false" to the camel-http4 producer endpoint URI, but also invoked the following code to explicitly set header "CamelHttpChunked" to false:

exchange.getIn().setHeader(Exchange.HTTP_CHUNKED, false);

However, the data sent to the server side from the camel-http4 producer endpoint was always chunked.

When directly using Httpcomponents-client V4.5 API, it is possible to disable chunking. for instance, this example:
https://github.com/apache/httpcomponents-client/blob/4.5.x/httpclient/src/examples/org/apache/http/examples/client/ClientChunkEncodedPost.java
When modify the line #58 to

reqEntity.setChunked(false);

Then it is possible to disable chunking.