Struts currently accepts both action!method.action and action!doMethod.action and will delegate them to doMethod(). However, the documentation doesn't explain this, and release notes and previous issues suggest that this is specifically unsupported.
It would be nice to have a summary of whether this is supported for the long-term, still targeted for removal or a bug.
The Release Notes 2.0.0 say:
try to execute submit method in the action, fail
WW-1423 specifically requests that behaviour be changed but, as of 126.96.36.199, DefaultActionInvocation will still retry doSubmit.