Upgrade plexus-compiler-javac-errorprone to 2.8.6 and error_prone_core to 2.3.4

Change-Id: Iebd128f979d977549763284e4f696a29d251f0d4

pom.xml

diff --git a/pom.xml b/pom.xml
index 385221f..f2aa17a 100644
--- a/pom.xml
+++ b/pom.xml
@@ -393,14 +393,14 @@
           <dependency>
             <groupId>org.codehaus.plexus</groupId>
             <artifactId>plexus-compiler-javac-errorprone</artifactId>
-            <version>2.8.5</version>
+            <version>2.8.6</version>
           </dependency>
           <!-- override plexus-compiler-javac-errorprone's dependency on
                Error Prone with the latest version -->
           <dependency>
             <groupId>com.google.errorprone</groupId>
             <artifactId>error_prone_core</artifactId>
-            <version>2.3.2</version>
+            <version>2.3.4</version>
           </dependency>
         </dependencies>
       </plugin>