HTTPCLIENT-1164: If we uncompress an entity on-the-fly, we should also remove its Content-MD5 header, as it will likely no longer be accurate, and an upstream consumer may incorrectly reject the response on that basis. This way the decorator preserves semantic transparency.
httpcomponents/httpclient/trunk/httpclient/src/main/java/org/apache/http/impl/client/CompressionDecorator.java