retrofix rxjava gson start-kit

build.gradle

apply plugin: 'com.android.library'
apply plugin: 'kotlin-android'

android {
    compileSdkVersion 27

    defaultConfig {
        minSdkVersion 14
        targetSdkVersion 27
        versionCode 1
        versionName "1.0"

        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"

    }

    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }

}

ext.retrofitsVer = '2.4.0'

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])

    implementation 'com.android.support:appcompat-v7:27.1.1'
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'com.android.support.test:runner:1.0.1'
    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.1'

    implementation 'io.reactivex.rxjava2:rxandroid:2.0.2'
    implementation 'io.reactivex.rxjava2:rxjava:2.1.12'
    implementation 'com.google.code.gson:gson:2.8.2'
    implementation "com.squareup.retrofit2:retrofit:$retrofitsVer"
    implementation "com.squareup.retrofit2:converter-gson:$retrofitsVer"
    implementation "com.squareup.retrofit2:adapter-rxjava2:$retrofitsVer"
    compile "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
}
repositories {
    mavenCentral()
}

RetrofitFacade.kt

package tech.igrant.rxjavaretrofitgson

import retrofit2.converter.gson.GsonConverterFactory
import retrofit2.Retrofit
import retrofit2.adapter.rxjava2.RxJava2CallAdapterFactory
import java.util.HashMap


class RetrofitFacade private constructor() {

    companion object {

        @Volatile
        private var retrofitMap: MutableMap<String, Retrofit> = HashMap()

        private val converter: GsonConverterFactory = GsonConverterFactory.create()
        private val callAdapterFactory: RxJava2CallAdapterFactory = RxJava2CallAdapterFactory.create()

        fun get(url: String): Retrofit {
            synchronized(retrofitMap, {
                if (!retrofitMap.containsKey(url)) {
                    retrofitMap[url] = Retrofit.Builder().baseUrl(url).addConverterFactory(converter).addCallAdapterFactory(callAdapterFactory).build()
                }
                return retrofitMap[url]!!
            })
        }
    }
}