IssueTracker

Thank you for the report, and sorry for any inconvenience. While reproducing the issue, one workaround I found is: -keeppackagenames com.example.customview.extra** (i.e., double asterisks, instead of single).

https://www.guardsquare.com/en/products/proguard/manual/usage#filters

R8 currently regards <package_filter> in that directive as <class_filter>. That's why single asterisk---a class name not containing the package separator---doesn't work for now, whereas double asterisks---matches a class name, possibly containing any number of package separators---works. The caveat is, use of, e.g., extra**, will keep all the sub packages as well. :( We'll prepare the fix soon.

Project: r8
Branch: master

commit a9a9e7d1231726094c6e16c2cef1bad887da3bba
Author: Jinseong Jeon <jsjeon@google.com>
Date:   Tue Apr 09 11:49:28 2019

    Reproduce b/130135768: keeppackagenames with asterisks
   
    Bug: 130135768
    Change-Id: I5ab1cdb5148a570a63bdd488358759bb33da700a

M       src/test/java/com/android/tools/r8/TestShrinkerBuilder.java
A       src/test/java/com/android/tools/r8/naming/KeepPackageNamesTest.java
A       src/test/java/com/android/tools/r8/naming/keeppackagenames/Top.java
A       src/test/java/com/android/tools/r8/naming/keeppackagenames/sub/SubClass.java

https://r8-review.googlesource.com/36860

Project: r8
Branch: master

commit 391e2992aee375adf46edbb5e7b098556c8604ed
Author: Søren Gjesse <sgjesse@google.com>
Date:   Fri Apr 12 11:05:43 2019

    New implementation of -keeppackagenames
   
    This implementation collects the list of package names given for
    -keeppackagenames and matches against that in the minifier.
   
    The previous implementation created class matching rules to piggybag
    on the existing matching.
   
    Bug: 130135768
    Change-Id: I5a341e145747a5dec8788a066a0c67d4e259ec77

M       src/main/java/com/android/tools/r8/graph/DexType.java
M       src/main/java/com/android/tools/r8/naming/ClassNameMinifier.java
M       src/main/java/com/android/tools/r8/shaking/ProguardConfiguration.java
M       src/main/java/com/android/tools/r8/shaking/ProguardConfigurationParser.java
D       src/main/java/com/android/tools/r8/shaking/ProguardKeepPackageNamesRule.java
A       src/main/java/com/android/tools/r8/shaking/ProguardPackageMatcher.java
A       src/main/java/com/android/tools/r8/shaking/ProguardPackageNameList.java
M       src/main/java/com/android/tools/r8/shaking/RootSetBuilder.java
M       src/test/java/com/android/tools/r8/naming/KeepPackageNamesTest.java
M       src/test/java/com/android/tools/r8/shaking/ProguardConfigurationParserTest.java
A       src/test/java/com/android/tools/r8/shaking/ProguardPackageNameMatcherTest.java

https://r8-review.googlesource.com/36944

Project: r8
Branch: d8-1.4

commit b6ca9ee953e43aa029411bb4db030e4694180063
Author: Christoffer Quist Adamsen <christofferqa@google.com>
Date:   Fri Apr 12 12:51:40 2019

    Version 1.4.86
   
    Cherry pick: New implementation of -keeppackagenames
    CL: https://r8-review.googlesource.com/c/r8/+/36944
   
    Cherry pick: Reproduce b/130135768: keeppackagenames with asterisks
    CL: https://r8-review.googlesource.com/c/r8/+/36860
   
    Bug: 130135768
    Change-Id: I8a340afe4811ec3f8826956c99b94346f4c2c8b4

M       src/main/java/com/android/tools/r8/Version.java
M       src/main/java/com/android/tools/r8/graph/DexType.java
M       src/main/java/com/android/tools/r8/naming/ClassNameMinifier.java
M       src/main/java/com/android/tools/r8/shaking/ProguardConfiguration.java
M       src/main/java/com/android/tools/r8/shaking/ProguardConfigurationParser.java
D       src/main/java/com/android/tools/r8/shaking/ProguardKeepPackageNamesRule.java
A       src/main/java/com/android/tools/r8/shaking/ProguardPackageMatcher.java
A       src/main/java/com/android/tools/r8/shaking/ProguardPackageNameList.java
M       src/main/java/com/android/tools/r8/shaking/RootSetBuilder.java
M       src/test/java/com/android/tools/r8/TestShrinkerBuilder.java
A       src/test/java/com/android/tools/r8/naming/KeepPackageNamesTest.java
A       src/test/java/com/android/tools/r8/naming/keeppackagenames/Top.java
A       src/test/java/com/android/tools/r8/naming/keeppackagenames/sub/SubClass.java
M       src/test/java/com/android/tools/r8/shaking/ProguardConfigurationParserTest.java
A       src/test/java/com/android/tools/r8/shaking/ProguardPackageNameMatcherTest.java

https://r8-review.googlesource.com/36959

This fix has been pushed to our 1.4 branch and will make it into a later release of AS 3.4.
You can try it out locally by amending your build.gradle as follows:

buildscript {
    repositories {
        maven {
            url 'http://storage.googleapis.com/r8-releases/raw'
        }
    }
    dependencies {
        classpath 'com.android.tools:r8:1.4.81'  // Must be before the Gradle Plugin for Android.
        classpath 'com.android.tools.build:gradle:...'
     }
}