If you are using ProGuard you might need to add the following options:

-dontwarn okhttp3.**
-dontwarn okio.**
-dontwarn javax.annotation.**
-dontwarn org.conscrypt.**

A resource is loaded with a relative path so the package of this class must be preserved.

-keepnames class okhttp3.internal.publicsuffix.PublicSuffixDatabase

Retrofit 2.X

https://square.github.io/retrofit/

-dontwarn retrofit2.**
-keep class retrofit2.** { *; }
-keepattributes Signature
-keepattributes Exceptions

-keepclasseswithmembers class * {
@retrofit2.http.* <methods>;
}