[CAMEL-14602] Removed String headers appears in next endpoints

• Type: Bug
• Status: Resolved
• Priority: Minor
• Resolution: Invalid
• Affects Version/s: 2.22.5
• Component/s: camel-core
• Estimated Complexity: Unknown
• Assignee: Unassigned
• Reporter: Vladislav Sokolov
• Created: 20/Feb/20 16:33
• Updated: 20/Feb/20 18:33
• Resolved: 20/Feb/20 18:33

Description

Hello,

I create this issue because we noticed a strange behaviour with headers in apache camel. 
I say "strange behaviour" because we didn't find anything in documentation about it. Maybe it's a normal behaviour, and we would like to see the part of documentation which talks about it.

Context

In our project, we have a bean which computes next endpoints and gives them to the recipientList. It looks like this :

<routes>
    <route>
       <!-- our logic -->
        <recipientList>
            <method ref="ourBean" method="ourMethod"/>
        </recipientList>
    </route>
</routes>

In ourMethod(), we manipulate headers(create, modify, remove).

Issue

However, inside ourMethod(), when we remove a header with

 exchange.getIn().removeHeader(headerToRemove)

The removed headers appears again in the next route.

 

ourMethod looks like this :

public String ourMethod(Exchange exchange,@Header("ourHeader") String headerToRemove) {
   //some logic

    if (!StringUtils.isEmpty(headerToRemove)){
      //some logic
      exchange.getIn().removeHeader(headerToRemove);
    }
}

So with this code, the header is removed from exchange, but re-appears in the next endpoint.

We have a workaround :

public String ourMethod(Exchange exchange,@Header("ourHeader") String headerToRemove) {
   //some logic

    if (!StringUtils.isEmpty(headerToRemove)){
      //some logic
      exchange.getIn().setHeader(headerToRemove, "");
    }
}

Instead of removing it, we set its value to an empty string.

Explanations

We're puzzled, we don't understand if this should be a correct behaviour or not. If yes, can you give us some explanations ?

Best Regards,
Vlad