Question

I have a maven multi-module pom which builds a war. I want to declare a provided scope dependecy on jsp-api in the parent pom. Maven docs suggest that dependencies declared as provided are not transitive, so:

Do I therefore need to go through all the sub-module poms and declare a provided dependency? There are ~40 modules in the project and it’s not immediately clear which will need the dependency, so this seems like quite alot of effort to achieve not very much and I am lazy. How are you handling this situation in your projects?

–Edit–

So for others reference this was happening because the parent pom was defining all dependencies in a dependencyManagment section. I’d not come across this before but it helps with cutting down duplication of complex dependencies with excludes or other non-trivial attributes. It also overrides the inheritance mechanism. As I understand it then, a good rule of thumb is to only use it to solve a problem don’t just chuck all your dependencies in there as the author of this pom had done. Perhaps a suitable maven expert could confirm this.

Answer 1

Even though provided scope dependencies are not transitive they may be inherited. That is to say, if you have module A with a provided scope dependency, and module B has a dependency on A, module B will not implicitly have the provided scope dependency. However, I believe that if module C has module A as a parent pom, it should inherit that dependency as normal.

You can verify this behavior yourself by running mvn help:effective-pom on one of the child poms, the effective-pom goal should give you a fully resolved view of the pom you run it on, taking into account inheritance, equivalent to what maven will actually use when it runs. If the <dependency> shows up there (as it seems to in my experiments) you should be fine specifying the dependency only in the parent pom.