[CAMEL-20429] setBody clears/invalidates streamcache still being used in header/property

• Type: Bug
• Status: Resolved
• Priority: Minor
• Resolution: Information Provided
• Affects Version/s: 4.0.3
• Component/s: came-core
• Estimated Complexity: Unknown
• Assignee: Unassigned
• Reporter: Rik van Ballegooijen
• Created: 16/Feb/24 11:02
• Updated: 10/Mar/24 11:25
• Resolved: 10/Mar/24 11:25

Description

While upgrading from camel 3 to 4 we ran into a stream cache related issue. An input stream containing the content of a HTML file is emptied/closed/invalidated after setting the exchange body to something different, even though the input stream is still in use, for example in a header.

<setHeader name="CamelThymeleafTemplate">
    <simple>${exchangeProperty.templateContents}</simple>
</setHeader>
<log message="CamelThymeleafTemplate after header set: ${headers.CamelThymeleafTemplate}" />
<setBody>
    <exchangeProperty>templateData</exchangeProperty>
</setBody>
<log message="CamelThymeleafTemplate before thymeleaf endpoint: ${headers.CamelThymeleafTemplate}" /> 

In the example above the first log statement will print the content of the HTML file, the 2nd log statement will print an empty header. No errors are thrown.

As a workaround, changing the type to a String fixes the issue:

<simple resultType="java.lang.String">${exchangeProperty.templateContents}</simple>

Is the stream cache discarded too soon? If we are not supposed to use it anymore after resetting the body I would expect an error of some sort rather than an empty result.