Unable to avoid searching for invalid dependency in gradle build

Question

I try to include the Launch4J gradle plugin in our project.

plugins {
    id 'edu.sc.seis.launch4j' version '2.4.8'
}

However, the build fails with the following error.

Could not resolve all files for configuration ':compileClasspath'. Could not find jai_core-1.1.3.jar (javax.media:jai_core:1.1.3). Searched in the following locations: https://jcenter.bintray.com/javax/media/jai_core/1.1.3/jai_core-1.1.3.jar

Looking at the jcenter repository, the file is indeed missing. (But why does gradle not search the next repository in the list for it?)

So I try to exclude that dependency from jcenter like this:

jcenter() {
    content {
        excludeGroupByRegex "javax.media.*"
    }
}

...but still the same error.

I also tried to exclude the dependency from the plugin repository in settings.gradle like this:

pluginManagement {
    repositories {
        jcenter() {
            content {
                excludeGroupByRegex "javax.media.*"
            }
        }
    }
}

...but still the same error.

How can I include edu.sc.seis.launch4j but retrieve jai_core from a different repository?

I expect gradle to search for the dependency in the next repository in the list if it is not present or excluded in the current one.