I can implement this. But there's one problem: the build start notification of the instant-messaging plugins is running before the build name setter plugin gets the chance to set the build name.
So the name reported at build start is always the default name, while the one on build end is the customized name.

I'm currently musing if this isn't a too confusing behaviour for users.

Maybe you could include both for the end report - e.g. keep the build# and put the build in name in parenthesis after it, or vice-versa.

I guess, I'll just take whatever is available and wait if someone complains about the inconsistent behaviour

After all, it only affects users which use the build name setter and have both of pre- and post-build notifications enabled.

Sounds good! Thanks

Code changed in jenkins
User: Christoph Kutzinski
Path:
src/main/java/hudson/plugins/im/build_notify/DefaultBuildToChatNotifier.java
src/main/java/hudson/plugins/im/build_notify/SummaryOnlyBuildToChatNotifier.java
src/main/resources/hudson/plugins/im/build_notify/Messages.properties
http://jenkins-ci.org/commit/instant-messaging-plugin/8241564a92d342259ae4c95b1467b45998fb0188
Log:
[FIXED JENKINS-11419] support custom build names

Integrated in plugins_instant-messaging #98
[FIXED JENKINS-11419] support custom build names

Christoph Kutzinski :
Files :

• src/main/java/hudson/plugins/im/build_notify/SummaryOnlyBuildToChatNotifier.java
• src/main/resources/hudson/plugins/im/build_notify/Messages.properties
• src/main/java/hudson/plugins/im/build_notify/DefaultBuildToChatNotifier.java

So how does one customize the messages now? I think I need the same feature.