Revert "Upgrade kotlin version to 1.6.20 (#3762)"

This reverts commit fd109a8.

This change broke kotlindoc generation, will have to fix it before
upgrading again.

Author: vkryachko

build.gradle

@@ -16,7 +16,7 @@ import com.google.firebase.gradle.plugins.license.LicenseResolverPlugin
 import com.google.firebase.gradle.MultiProjectReleasePlugin
 
 buildscript {
-    ext.kotlinVersion = '1.6.20'
+    ext.kotlinVersion = '1.3.72'
     repositories {
         google()
         mavenCentral()

buildSrc/build.gradle

@@ -51,7 +51,7 @@ dependencies {
     implementation "com.google.auto.value:auto-value-annotations:1.7"
     annotationProcessor "com.google.auto.value:auto-value:1.6.5"
     implementation 'digital.wup:android-maven-publish:3.6.3'
-    implementation 'org.jetbrains.kotlin:kotlin-gradle-plugin:1.6.20'
+    implementation 'org.jetbrains.kotlin:kotlin-gradle-plugin:1.3.72'
     implementation 'org.json:json:20180813'
 
     implementation "org.eclipse.aether:aether-api:1.0.0.v20140518"

buildSrc/src/main/java/com/google/firebase/gradle/plugins/LibraryType.java

@@ -29,14 +29,6 @@ public String getFormat() {
   }
 
   public String getComponentName() {
-    // Due to the fact that multiple components are created for android libraries(1 per variant),
-    // the "android" component contains artifacts from all 3 variants for Kotlin libraries, which is
-    // invalid(bug in
-    // https://github.com/wupdigital/android-maven-publish ?).
-    // So we explicitly choose the "Release" variant for android libraries.
-    if (this == ANDROID) {
-      return name().toLowerCase() + "Release";
-    }
     return name().toLowerCase();
   }
 }

encoders/protoc-gen-firebase-encoders/protoc-gen-firebase-encoders.gradle

@@ -36,8 +36,8 @@ dependencies {
     implementation "com.google.protobuf:protobuf-java:3.14.0"
     implementation 'com.squareup:javapoet:1.13.0'
     implementation 'com.google.guava:guava:30.0-jre'
-    implementation 'com.google.dagger:dagger:2.39.1'
-    kapt 'com.google.dagger:dagger-compiler:2.39.1'
+    implementation 'com.google.dagger:dagger:2.31.2'
+    kapt 'com.google.dagger:dagger-compiler:2.31.2'
 
     testImplementation 'junit:junit:4.13.1'
     testImplementation "com.google.truth:truth:1.0.1"

firebase-common/ktx/ktx.gradle

@@ -36,7 +36,7 @@ android {
 }
 
 dependencies {
-    implementation "org.jetbrains.kotlin:kotlin-stdlib:$kotlinVersion"
+    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlinVersion"
 
     implementation project(':firebase-common')
     implementation project(':firebase-components')

tools/lint/lint.gradle

@@ -19,7 +19,6 @@ plugins {
 def lintVersion = '26.4.1'
 
 dependencies {
-  compileOnly "org.jetbrains.kotlin:kotlin-stdlib:$kotlinVersion"
   compileOnly "com.android.tools.lint:lint-api:$lintVersion"
   compileOnly "com.android.tools.lint:lint-checks:$lintVersion"