camel-jetty exception for pass through route: 'Header>6144'

Issue

We have a HTTP pass through Camel route using camel-jetty.

<from uri="jetty://http://0.0.0.0:9000/test/controls" />
<to uri="http://target:80/testing/?bridgeEndpoint=true" />

Requests are being sent from client with Content-Type "application/x-www-form-urlencoded".
A rather large payload 7KB (URL encoded XML string) is coming in incoming request I think it comes in a arbitrary designated header 'formMetaData' in the incoming request. When the HTTP request gets to Fuse we see an error:

 header full: java.lang.RuntimeException: Header>6144