Is it possible to have an optional header on a provider wsd?
If I add a handler to a provider wsd and the header it handles to an operation, it is always a required header.
Is there a way to set required to false?

I’m not talking about the contents of the header, but about the complete header.

did you try to set:
soap:mustUnderstand=“0|1”
0 means it’s optional

just noticed this line in the “Web Services Developer’s Guide” :

“Note: Integration Server considers all of the headers defined in a web service descriptor
to be required. If the header does not exist in the SOAP message at run time, Integration
Server throws an error.”

For WM IS, Even you can set Must Understand=true or false, the client still need to send all headers defined.