Jetty 12 IllegalArgumentExeption when setting a HTTP header to null

[ekupcik]

Jetty version(s)
12.0.1

Description
In jetty 12.0.1 calling HttpServletResponse.addHeader("name", null) throws an IllegalArgumentException

java.lang.IllegalArgumentException: null value
at org.eclipse.jetty.http.HttpFields$Mutable.add(HttpFields.java:901) ~[?:?]
at org.eclipse.jetty.ee10.servlet.ServletApiResponse.addHeader(ServletApiResponse.java:217) ~[?:?]

This used to work till 12.0.0 in Jetty, works in Tomcat and i also found this description jakartaee/servlet#159 This seems to be a regression

[joakime]

When you use HttpServletResponse.addHeader(name, value) you are adding a value to a list of values for a header.

Using HttpServletResponse.addHeader("X-Foo", null) would attempt to add a null value to the list of values to the header X-Foo.
That's invalid, hence the IllegalArgumentException

Note: If you had used HttpServletResponse.setHeader("X-Foo", null) then you are essentially removing that header (you are setting the header to have no value or values, which eliminates it)

[joakime]

The linked spec issue jakartaee/servlet#159 is about setHeader() not addHeader() btw.

[joakime]

The javadoc for the various setHeader / addHeader (and variants) calls out behavior when nulls are passed as parameters.

PR incoming.

[joakime]

Opened PR #10510 to address this

[janbartel]

Fixed via #10510