Use toStringUtf8 on a ByteString to get the actual string for use in an
exception, instead of toString which just prints something like
"<ByteString@609cd4d8 size=42>".

RELNOTES: None.
PiperOrigin-RevId: 225079501

src/tools/android/java/com/google/devtools/build/android/aapt2/ProtoApk.java

diff --git a/src/tools/android/java/com/google/devtools/build/android/aapt2/ProtoApk.java b/src/tools/android/java/com/google/devtools/build/android/aapt2/ProtoApk.java
index 7ac705e..7c72027 100644
--- a/src/tools/android/java/com/google/devtools/build/android/aapt2/ProtoApk.java
+++ b/src/tools/android/java/com/google/devtools/build/android/aapt2/ProtoApk.java
@@ -304,7 +304,7 @@
       }
       throw new IllegalStateException(
           "Unable to find prefix for "
-              + uri
+              + uri.toStringUtf8()
               + " in [ "
               + namespaceStack.stream()
                   .map(Map::keySet)