Switch to Mockito Core and update to latest version. (#2877)

java/pom.xml

@@ -237,10 +237,9 @@
     </dependency>
     <dependency>
       <groupId>org.mockito</groupId>
-      <artifactId>mockito-all</artifactId>
-      <version>1.10.19</version>
+      <artifactId>mockito-core</artifactId>
+      <version>2.23.4</version>
       <scope>test</scope>
     </dependency>
   </dependencies>
-
 </project>