Remove unused AutoValue dependency. (#392)

Remove unused AutoValue dependency (and remove Java 8 API dependency which was accidentally introduced).

Author: micahstairs

pom.xml

@@ -321,13 +321,6 @@
                 <configuration>
                     <source>1.7</source>
                     <target>1.7</target>
-                    <annotationProcessorPaths>
-                        <path>
-                            <groupId>com.google.auto.value</groupId>
-                            <artifactId>auto-value</artifactId>
-                            <version>1.7</version>
-                        </path>
-                    </annotationProcessorPaths>
                 </configuration>
             </plugin>
             <plugin>
@@ -433,11 +426,6 @@
         </dependency>
 
         <!-- Utilities -->
-        <dependency>
-            <groupId>com.google.auto.value</groupId>
-            <artifactId>auto-value-annotations</artifactId>
-            <version>1.7</version>
-        </dependency>
         <dependency>
             <groupId>com.google.guava</groupId>
             <artifactId>guava</artifactId>

src/main/java/com/google/firebase/auth/FirebaseUserManager.java

@@ -33,6 +33,7 @@
 import com.google.api.client.json.JsonObjectParser;
 import com.google.api.client.util.Key;
 import com.google.common.annotations.VisibleForTesting;
+import com.google.common.base.Joiner;
 import com.google.common.base.Strings;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
@@ -271,7 +272,7 @@ private static String generateMask(Map<String, Object> properties) {
     // since we do not currently generate masks for any properties with nested values. When it
     // comes time to implement this, we can check if a property has nested properties by checking
     // if it is an instance of the Map class.
-    return String.join(",", ImmutableSortedSet.copyOf(properties.keySet()));
+    return Joiner.on(",").join(ImmutableSortedSet.copyOf(properties.keySet()));
   }
 
   void deleteTenant(String tenantId) throws FirebaseAuthException {