Gump can be configured to send out e-mails to anywhere based on finding any regular expression of your choosing in the output web page. This most often is done to inform developers of build or test failures. While the appropriate response to each message will depend on the individual circumstances, generally the correct response involves actually talking to someone about it.
In short, Gump doesn't tell you what to do, but it does tend to let you know when would be a good time to actually talk to someone about a change that might impact you.
This is actually the most common type of error found by Gump. Somebody checked something in and it either doesn't compile outright, or doesn't work with some other change within the same project. The most common instance of this is somebody creating a new file on their machine and forgetting to add it to cvs.
While in an ideal world, this should never happen, and people should verify every change before committing, realize that it happens to all of us. What is important is that it is quickly responded to.
These problems are comparatively infrequent, but when you track enough projects, there generally is an instance of this somewhere. And if it is somewhere, Gump will generally find it.
The first thing to realize is that the Gump message is merely informational. The correct response may be to convince the project that made the change to consider another design alternative that is backwards compatible. As a general rule, this is the preferred approach
For some changes, this may not be practical. For others, the API in question may actually have already been deprecated for an extended period of time, and is now just finally being removed. Many times, you can find a change which works with both the old and new version. This is ideal as it helps decouple the releases - people who keep current with your software can choose when they want to upgrade your dependencies.
When all else fails, you need to make a choice as to how to proceed. Keeping up with the absolute latest changes is probably the way to go if the next release of your software is likely to be a ways off. If, on the other hand, you are close to a release boundary - holding off until after you release is likely the prudent approach. Unless you ask for the reminders to be turned off, you will continue to be reminded, but remember it is up to you to decide what to do with this information.
Gump is software, and therefore may introduce bugs. It also may build your project in a way different than you traditionally do. In particular, the dependencies must be declared to Gump prior to the build, and can not change during the course of a build.
The most common occurrence of problems here is introducing a new dependency without the Gump project definition being updated. A note to general@gump.apache.org letting us know what is going on is appreciated when this occurs.
Of course, you should always send e-mail if you suspect that Gump itself is the cause.