Update to protobuf 3.10 lite.

build.gradle

@@ -1,7 +1,7 @@
 subprojects {
-    ext.version_number   = "0.1.2"
+    ext.version_number   = "0.0.5-PROTOBUF3"
     ext.group_info       = "org.signal"
-    ext.protocol_version = "2.8.1"
+    ext.protocol_version = "2.7.1-PROTOBUF3"
 
     if (JavaVersion.current().isJava8Compatible()) {
         allprojects {

java/build.gradle

@@ -1,7 +1,7 @@
 buildscript {
     repositories {
         google()
-        mavenCentral()
+        jcenter()
     }
 
     dependencies {

java/src/main/java/org/signal/libsignal/metadata/certificate/SenderCertificate.java

@@ -79,7 +79,7 @@ public class SenderCertificate {
   }
 
   public String getSender() {
-    return senderE164.or(senderUuid).orNull();
+    return senderUuid.or(senderE164).orNull();
   }
 
   public long getExpiration() {

java/src/main/java/org/signal/libsignal/metadata/protocol/UnidentifiedSenderMessage.java

@@ -4,6 +4,7 @@ package org.signal.libsignal.metadata.protocol;
 import com.google.protobuf.ByteString;
 import com.google.protobuf.InvalidProtocolBufferException;
 
+import org.omg.CORBA.DynAnyPackage.Invalid;
 import org.signal.libsignal.metadata.InvalidMetadataMessageException;
 import org.signal.libsignal.metadata.InvalidMetadataVersionException;
 import org.signal.libsignal.metadata.SignalProtos;