The gradle Wrapper task creates the gradle wrapper scripts, but it does so in the project root, which sometimes is not wanted. One can override it, so that the scripts are found in, say, a 'contrib' folder, along with other helper scripts.
Jenkins Gradle plugin has the option to use the wrapper, but it blindly tries to invoke gradlew from the project root - it is unaware of custom settings.
Please let users define a custom path to the gradlew script within the project, or, ideally, read if somehow from the build.gradle file (it might be difficult, I aggree). Having users specify it explicitly is good enough, IMHO.