Strips mappings from proguard file

build.gradle

tasks.register("proguardMapper", ProguardMappingMapperTask::class).configure {
    outputFile = project.rootProject.file("app/build/outputs/mapping/release/mapping-striped.txt")
    mappingFile = project.rootProject.file("app/build/outputs/mapping/release/mapping.txt")
}

datadog {
    mappingFilePath = "${project.buildDir}/outputs/mapping/release/mapping-striped.txt"
}

ProguardMappingMapperTask.kt

package com.mycompany.gradle.tasks

import org.gradle.api.DefaultTask
import org.gradle.api.GradleException
import org.gradle.api.tasks.InputFile
import org.gradle.api.tasks.Optional
import org.gradle.api.tasks.OutputFile
import org.gradle.api.tasks.TaskAction
import java.io.File

// issue: The proguard mapping file at: [/home/circleci/app/app/build/outputs/mapping/release/mapping.txt] size exceeded the maximum 50 MB size. This task cannot be performed.
// This task aims to remove disallowed mappings from the proguard file.
open class ProguardMappingMapperTask : DefaultTask() {

    companion object {
        private val allowedPackages = listOf("com.mycompany")

        // '#' defines additional metadata to the parser.
        // ' ' is a signal that line is the not a class mapping. Usually a class body mapping or a comment.
        private val knownNonClassMappingFirstChars = listOf(' ', '#')

        /*
            stripDisallowedPackages reads a proguard mapping file and writes all allowed proguard mappings to an output file.

            Input:

            # compiler: R8
            # compiler_version: 2.2.66
            # min_api: 24
            # pg_map_id: 94b8e40
            # common_typos_disable
            androidx.appcompat.app.ActionBarDrawerToggle$Delegate -> obfuscated.m0$b:   # Below  shows which if statement is true in forEachLine
              android.content.Context getActionBarThemedContext() -> a                  <-- if !isNonClassMapping
            com.mycompany.analytics.ApptimizeTestRunner -> obfuscated.yn7:                  <-- if isAllowedPackage
            # {"id":"sourceFile","fileName":"ApptimizeTestRunner.kt"}                   <-- if isInAllowedPackageMapping && isNonClassMapping
              1:1:void <init>():8:8 -> <init>
              1:1:boolean getBooleanOrDefault(java.lang.String,boolean):16:16 -> a
            org.socure.core.MatOfDouble -> obfuscated.kuq:                              <-- if !isNonClassMapping
            # {"id":"sourceFile","fileName":"SourceFile"}
              1:1:void <init>() -> <init>

            Output:

            com.mycompany.analytics.ApptimizeTestRunner -> obfuscated.yn7:
            # {"id":"sourceFile","fileName":"ApptimizeTestRunner.kt"}
              1:1:void <init>():8:8 -> <init>
              1:1:boolean getBooleanOrDefault(java.lang.String,boolean):16:16 -> a
         */
        private fun stripDisallowedPackages(outputFile: File, mappingFile: File) {
            // Create or clear output file.
            outputFile.writeText("")
            var isInAllowedPackageMapping = false
            mappingFile.forEachLine { line ->
                val isAllowedPackage = allowedPackages.any { line.startsWith(it) }
                val isNonClassMapping = knownNonClassMappingFirstChars.any { it == line.first() }
                if (isAllowedPackage) {
                    isInAllowedPackageMapping = true
                    outputFile.appendText(line + "\n")
                } else if (isInAllowedPackageMapping && isNonClassMapping) {
                    outputFile.appendText(line + "\n")
                } else if (!isNonClassMapping) {
                    isInAllowedPackageMapping = false
                }
            }
            println("${mappingFile.name}: ${mappingFile.length()} bytes")
            println("${outputFile.name}: ${outputFile.length()} bytes")
        }
    }

    @get:OutputFile
    @Optional
    var outputFile: File? = null

    @get:InputFile
    @Optional
    var mappingFile: File? = null

    @TaskAction
    fun runTask() {
        if (outputFile == null) {
            throw GradleException("Output file is null")
        }

        if (mappingFile == null || !mappingFile!!.isFile) {
            throw GradleException("Mapping file is null or missing")
        }

        stripDisallowedPackages(outputFile!!, mappingFile!!)
    }
}