kn trigger update --help information is incorrect

[paulyhedral]

Bug report

kn trigger update --help implies that updating the broker is possible, but when

kn trigger update trigger-name --broker broker-name

is executed, the following error is output:

Error: cannot update trigger 'example-trigger' because broker is immutable

Expected behavior

If the broker is immutable on a trigger, then the help information for update should not indicate that it is available as an option.

Steps to reproduce the problem

kn version

Version:      v1.10.0
Build Date:   2023-04-26 10:17:21
Git Revision: 46dbf661
Supported APIs:
* Serving
  - serving.knative.dev/v1 (knative-serving v1.10.0)
* Eventing
  - sources.knative.dev/v1 (knative-eventing v1.10.0)
  - eventing.knative.dev/v1 (knative-eventing v1.10.0)

$ kn trigger update --help
Update a trigger

Usage:
  kn trigger update NAME [options]

Examples:

  # Update the filter which key is 'type' to value 'knative.dev.bar' in a trigger 'mytrigger'
  kn trigger update mytrigger --filter type=knative.dev.bar

  # Remove the filter which key is 'type' from a trigger 'mytrigger'
  kn trigger update mytrigger --filter type-

  # Update the sink of a trigger 'mytrigger' to 'ksvc:new-service'
  kn trigger update mytrigger --sink ksvc:new-service


Options:
      --broker string      Name of the Broker which the trigger associates with. (default "default")
      --filter strings     Key-value pair for exact CloudEvent attribute matching against incoming events, e.g type=dev.knative.foo
  -n, --namespace string   Specify the namespace to operate in.
  -s, --sink string        Addressable sink for events. You can specify a broker, channel, Knative service or URI. Examples: '--sink broker:nest' for a broker 'nest', '--sink channel:pipe' for a
                           channel 'pipe', '--sink ksvc:mysvc:mynamespace' for a Knative service 'mysvc' in another namespace 'mynamespace', '--sink https://event.receiver.uri' for an URI with an
                           'http://' or 'https://' schema, '--sink ksvc:receiver' or simply '--sink receiver' for a Knative service 'receiver' in the current namespace. If a prefix is not provided, it
                           is considered as a Knative service in the current namespace. If referring to a Knative service in another namespace, 'ksvc:name:namespace' combination must be provided explicitly.

Use "kn options" for a list of global command-line options (applies to all commands).

$ kn trigger update example-trigger --broker eventing-book
Error: cannot update trigger 'example-trigger' because broker is immutable
Run 'kn --help' for usage

Knative (serving/eventing) version

v1.10.0

[rhuss]

Thanks! This indeed a valid bug, there might have been some changes in the backend.

[dsimansk]

Thanks! This indeed a valid bug, there might have been some changes in the backend.

It seems Spec.Broker was always immutable field. We probably overlooked it. Thanks for the report!