网上添加的混淆过滤规则试了好多中都不能用，后来升级okhttp的版本至
implementation 'com.squareup.okhttp3:okhttp:3.14.0'
混淆规则：
#-------------- okhttp3 start-------------
# OkHttp3
# https://github.com/square/okhttp
# okhttp
-keepattributes Signature
-keepattributes *Annotation*
-keep class com.squareup.okhttp.* { *; }
-keep interface com.squareup.okhttp.** { *; }
-dontwarn com.squareup.okhttp.**
# okhttp 3
-keepattributes Signature
-keepattributes *Annotation*
-keep class okhttp3.** { *; }
-keep interface okhttp3.** { *; }
-dontwarn okhttp3.**
# Okio
-dontwarn com.squareup.**
-dontwarn okio.**
-keep public class org.codehaus.* { *; }
-keep public class java.nio.* { *; }
#----------okhttp end--------------