Update checkstyle to 8.10

- fix issues detected
  - YANG custom registrator should be subject to checkstyle
  - fix Java 8 syntax related violations

Change-Id: I0fc52c6612a40d851fd9bc3bf019621776b1f92a
diff --git a/lib/pom.xml b/lib/pom.xml
index d406833..581e2d3 100644
--- a/lib/pom.xml
+++ b/lib/pom.xml
@@ -956,7 +956,7 @@
                     <dependency>
                         <groupId>com.puppycrawl.tools</groupId>
                         <artifactId>checkstyle</artifactId>
-                        <version>6.19</version>
+                        <version>8.10</version>
                     </dependency>
                 </dependencies>
                 <configuration>