Add in SpotBugs plugin (#118)

* Add in SpotBugs plugin

Yet another stackic checker.
Fixes #78

* Let's use real versions

* Upgrade checkstyle version

pom.xml

@@ -17,15 +17,14 @@ limitations under the License.
   <modelVersion>4.0.0</modelVersion>
 
   <properties>
-    <currentVersion>1.0.14-SNAPSHOT</currentVersion>
     <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
     <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
     <javac.version>9+181-r4173-1</javac.version>
   </properties>
 
   <groupId>com.google.cloud.samples</groupId>
   <artifactId>shared-configuration</artifactId>
-  <version>${currentVersion}</version>
+  <version>1.0.14-SNAPSHOT</version>
   <packaging>pom</packaging>
 
   <name>${project.groupId}:${project.artifactId}</name>
@@ -74,7 +73,7 @@ limitations under the License.
     <connection>scm:git:git@github.com:GoogleCloudPlatform/java-repo-tools.git</connection>
     <developerConnection>scm:git:git@github.com:GoogleCloudPlatform/java-repo-tools.git</developerConnection>
     <url>git@github.com:GoogleCloudPlatform/java-repo-tools.git</url>
-    <tag>v${currentVersion}</tag>
+    <tag>v${project.version}</tag>
   </scm>
 
   <distributionManagement>
@@ -205,6 +204,28 @@ limitations under the License.
         </configuration>
       </plugin>
 
+      <plugin>
+        <groupId>com.github.spotbugs</groupId>
+        <artifactId>spotbugs-maven-plugin</artifactId>
+        <version>4.0.0</version>
+        <executions>
+          <execution>
+            <phase>verify</phase>
+            <goals>
+              <goal>check</goal>
+            </goals>
+          </execution>
+        </executions>
+        <dependencies>
+          <!-- overwrite dependency on spotbugs if you want to specify the version of spotbugs -->
+          <dependency>
+            <groupId>com.github.spotbugs</groupId>
+            <artifactId>spotbugs</artifactId>
+            <version>4.0.1</version>
+          </dependency>
+        </dependencies>
+      </plugin>
+
       <plugin> <!-- Style Check -->
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-checkstyle-plugin</artifactId>
@@ -225,12 +246,12 @@ limitations under the License.
           <dependency>
             <groupId>com.google.cloud.samples</groupId>
             <artifactId>checkstyle-configuration</artifactId>
-            <version>${currentVersion}</version>
+            <version>1.0.14-SNAPSHOT</version>
           </dependency>
           <dependency>
             <groupId>com.puppycrawl.tools</groupId>
             <artifactId>checkstyle</artifactId>
-            <version>8.30</version>
+            <version>8.31</version>
           </dependency>
         </dependencies>
         <executions>