Camel http producer fails when there are some unicode characters in the header values.

Issue

• HTTP operation failed invoking http://host:port/path with statusCode: 400

at org.apache.camel.component.http4.HttpProducer.populateHttpOperationFailedException(HttpProducer.java:313) ~[camel-http4-2.21.0.fuse-740039-redhat-00001.jar:2.21.0.fuse-740039-redhat-00001]
    at org.apache.camel.component.http4.HttpProducer.process(HttpProducer.java:208) ~[camel-http4-2.21.0.fuse-740039-redhat-00001.jar:2.21.0.fuse-740039-redhat-00001]
    at org.apache.camel.util.AsyncProcessorConverterHelper$ProcessorToAsyncProcessorBridge.process(AsyncProcessorConverterHelper.java:61) ~[camel-core-2.21.0.fuse-740039-redhat-00001.jar:2.21.0.fuse-740039-redhat-00001]
    at org.apache.camel.processor.SendProcessor.process(SendProcessor.java:148) ~[camel-core-2.21.0.fuse-740039-redhat-00001.jar:2.21.0.fuse-740039-redhat-00001]
    at org.apache.camel.processor.RedeliveryErrorHandler.process(RedeliveryErrorHandler.java:548) ~[camel-core-2.21.0.fuse-740039-redhat-00001.jar:2.21.0.fuse-740039-redhat-00001]
    at org.apache.camel.processor.CamelInternalProcessor.process(CamelInternalProcessor.java:201) [camel-core-2.21.0.fuse-740039-redhat-00001.jar:2.21.0.fuse-740039-redhat-00001]
    at org.apache.camel.processor.Pipeline.process(Pipeline.java:138) [camel-core-2.21.0.fuse-740039-redhat-00001.jar:2.21.0.fuse-740039-redhat-00001]
    at org.apache.camel.processor.Pipeline.process(Pipeline.java:101) [camel-core-2.21.0.fuse-740039-redhat-00001.jar:2.21.0.fuse-740039-redhat-00001]
    at org.apache.camel.processor.CamelInternalProcessor.process(CamelInternalProcessor.java:201) [camel-core-2.21.0.fuse-740039-redhat-00001.jar:2.21.0.fuse-740039-redhat-00001]
    at org.apache.camel.component.timer.TimerConsumer.sendTimerExchange(TimerConsumer.java:197) [camel-core-2.21.0.fuse-740039-redhat-00001.jar:2.21.0.fuse-740039-redhat-00001]
    at org.apache.camel.component.timer.TimerConsumer$1.run(TimerConsumer.java:79) [camel-core-2.21.0.fuse-740039-redhat-00001.jar:2.21.0.fuse-740039-redhat-00001]
    at java.util.TimerThread.mainLoop(Timer.java:555) [na:1.8.0_181]
    at java.util.TimerThread.run(Timer.java:505) [na:1.8.0_181]

• Characters that do not work include but not limited to И, ญ, Б, etc.