Change content of the file through JenkinsFile/pipeline

Question

buildTypes {
    debug {
        **debuggable true**
    }
    release {
        minifyEnabled enableProguardInReleaseBuilds
        signingConfig signingConfigs.release
        **debuggable false**
    }
    stagingRelease {
        minifyEnabled false
        proguardFiles getDefaultProguardFile("proguard-android.txt"), "proguard- 
        rules.pro"
        signingConfig signingConfigs.release
        **debuggable false**
        jniDebuggable false
    } 
    InternalRelease {
        initWith productionRelease
        applicationIdSuffix ".private"
    }
}

There are BuildType (above is content of one file in project) and in stagingRelease build type I wanted to make debuggable true when parameter is checked. So basically it's a file content change requirement. How do I fullfill it using jenkinspipeline or Jenkins job or some plugin, which finds some particular pattern of 3-4 lines and replace those 3-4?

Please provide some example through shell script or pipeline script(groovy) or python, or some links will really helpful.

stagingRelease {
    proguardFiles getDefaultProguardFile("proguard-android.txt"), "proguard-rules.pro"
    signingConfig signingConfigs.release
    debuggable false  // ***This should turn true, when I check flag in jenkins parameter.***
    jniDebuggable false
}