Android Gradle method to add sourcesets

Question

Currently I am developing an app with gradle and I have lots of different sourcesets for some different flavors. I am adding sourcesets in my build.gradle the following way:

sourceSets {
        debug {
            java.srcDirs += ['src/firstLib/common/java']
        }
        release {
            java.srcDirs += ['src/firstLib/common/java']
        }
}

Because I have lots of this blocks in my build.gradle I was wondering if there is an possibility to simply call a function which takes the sourcesets as a parameter and add it to the java.srcDirs. For example something like this:

void addToSourceSet(String parameter) {
    sourceSets {
        debug {
            java.srcDirs += [parameter]
        }
        release {
            java.srcDirs += [parameter]
        }
    }
}

Is this possible even if the method body isn't part of the gradle android-tag?