Update versions to 3.9.1

java/README.md

@@ -23,7 +23,7 @@ If you are using Maven, use the following:
 <dependency>
   <groupId>com.google.protobuf</groupId>
   <artifactId>protobuf-java</artifactId>
-  <version>3.8.0</version>
+  <version>3.9.1</version>
 </dependency>
 ```
 
@@ -37,7 +37,7 @@ protobuf-java-util package:
 <dependency>
   <groupId>com.google.protobuf</groupId>
   <artifactId>protobuf-java-util</artifactId>
-  <version>3.8.0</version>
+  <version>3.9.1</version>
 </dependency>
 ```
 
@@ -45,7 +45,7 @@ protobuf-java-util package:
 
 If you are using Gradle, add the following to your `build.gradle` file's dependencies:
 ```
-    compile 'com.google.protobuf:protobuf-java:3.8.0'
+    compile 'com.google.protobuf:protobuf-java:3.9.1'
 ```
 Again, be sure to check that the version number maches (or is newer than) the version number of protoc that you are using.