Camel 4.1.0 Invalid Content-Encoding Reproducer

This project was initialized from the camel Archetype as follow:

$ mvn archetype:generate -B \
    -DarchetypeGroupId=org.apache.camel.archetypes \
    -DarchetypeArtifactId=camel-archetype-java \
    -DarchetypeVersion=4.1.0 \
    -Dpackage=org.apache.camel \
    -DgroupId=org.apache.camel.reproducer \
    -DartifactId=reproducer-for-my-issue \
    -Dversion=1.0.0-SNAPSHOT

Issue Description

When a character set (aka charset) is defined on a call to an HTTP endpoint, that endpoint can incorrectly set the Content-Encoding header to that charset.

Here are the key conditions under which this happens:

The body of the message processed by the HTTP component is a String type
The following Java expression, evaludated by HttpProducer, is false: GZIPHelper.isGzip(exchange.getIn())

Building and Running the example

NOTE that port 9000 is used by this test, and must be unused on the system.

$ mvn clean install
$ mvn camel:run

Reading the results

The following log line is written when the invalid Content-Encoding header is detected.

INFO  *** INVALID CONTENT ENCODING DETECTED ***

Additional Tests

Here is a 1-liner that will run an additional test while the application is running:

curl --data-ascii 'hello' 'Content-Type: text/plain;charset=us-ascii' http://localhost:9000

Root Cause

The root cause of this bug is the following call made by HttpProducer:

answer = new StringEntity(content, contentType, charset, false);

Note the 3rd argument passed in, charset, is the character set (e.g. "UTF-8"). Here is the signature of that constructor; note that the 3rd argument is contentEncoding:

public StringEntity(
        final String string, final ContentType contentType, final String contentEncoding, final boolean chunked) {

orpiske / camel-invalid-content-encoding