2.9 snapshots ship with byte code level 58
What kind of issue is this?

 - [ ] Question. This issue tracker is not the place for questions. If you want to ask how to do
       something, or to understand why something isn't working the way you expect it to, use Stack
       Overflow. https://stackoverflow.com/questions/tagged/retrofit

 - [x] Bug report. If you’ve found a bug, spend the time to write a failing test. Bugs with tests
       get fixed. Here’s an example: https://gist.github.com/swankjesse/6608b4713ad80988cdc9

 - [ ] Feature Request. Start by telling us what problem you’re trying to solve. Often a solution
       already exists! Don’t send pull requests to implement new features without first getting our
       support. Sometimes we leave features out on purpose to keep the project small.

```
➜  retrofit-2.8.1 javap -v retrofit2.Retrofit\$Builder|grep major          
  major version: 52
➜  retrofit-2.9.SNAPSPOT javap -v retrofit2.Retrofit\$Builder|grep major         
  major version: 58
```

Based on the ASG thread, looks like snapshots are shipping w/ Java 1.4 byte code unintentionally.
It would be nice to get them back to 52 so that i can use snapshot version :)
build.gradle
build.gradle
diff --git a/build.gradle b/build.gradle
index d3dd0930dc..847eb2adc5 100644
--- a/build.gradle
+++ b/build.gradle
@@ -59,6 +59,12 @@ subprojects {
     jcenter()
   }
 
+  tasks.withType(JavaCompile).configureEach { task ->
+    task.options.encoding = 'UTF-8'
+    task.sourceCompatibility = JavaVersion.VERSION_1_8
+    task.targetCompatibility = JavaVersion.VERSION_1_8
+  }
+
   // Error-prone only works on JDK 11 or older currently.
   if (!Jvm.current().javaVersion.isJava12Compatible()) {
     apply plugin: 'net.ltgt.errorprone'
@@ -69,10 +75,6 @@ subprojects {
     }
 
     tasks.withType(JavaCompile).configureEach { task ->
-      task.options.encoding = 'UTF-8'
-      task.sourceCompatibility = JavaVersion.VERSION_1_8
-      task.targetCompatibility = JavaVersion.VERSION_1_8
-
       task.options.errorprone {
         excludedPaths = '.*/build/generated/source/proto/.*'
         check('MissingFail', CheckSeverity.ERROR)
