Added some static analysis tools to the build, fix a few bugs found

Server/pom.xml

@@ -84,6 +84,12 @@
       <version>2.0.0-beta6</version>
       <scope>compile</scope>
     </dependency>
+    <dependency>
+      <groupId>com.google.errorprone</groupId>
+      <artifactId>error_prone_annotations</artifactId>
+      <version>2.9.0</version>
+      <scope>compile</scope>
+    </dependency>
   </dependencies>
 
   <build>
@@ -190,6 +196,22 @@
         <configuration>
           <maxmem>1024m</maxmem>
           <useIncrementalCompilation>false</useIncrementalCompilation>
+		  <compilerArgs>
+			<arg>-XDcompilePolicy=simple</arg>
+			<!-- <arg>-Xplugin:ErrorProne</arg> uncomment when fixing java static analysis errors !-->
+		  </compilerArgs>
+		  <annotationProcessorPaths>
+			<path>
+			  <groupId>com.google.errorprone</groupId>
+			  <artifactId>error_prone_core</artifactId>
+			  <version>2.9.0</version>
+			</path>
+			<!-- Other annotation processors go here.
+
+			If 'annotationProcessorPaths' is set, processors will no longer be
+			discovered on the regular -classpath; see also 'Using Error Prone
+			together with other annotation processors' below. -->
+		  </annotationProcessorPaths>
         </configuration>
         <executions>
           <!-- Replacing default-compile as it is treated specially by maven -->
@@ -235,6 +257,48 @@
           <mainClass>rs09.Server</mainClass>
         </configuration>
       </plugin>
+        <plugin>
+            <groupId>org.apache.maven.plugins</groupId>
+            <artifactId>maven-antrun-plugin</artifactId>
+            <version>1.8</version>
+            <executions>
+                <execution>
+                    <!-- This can be run separately with mvn antrun:run@detekt -->
+                    <id>detekt</id>
+                    <phase>verify</phase>
+                    <configuration>
+                        <target name="detekt">
+                            <java taskname="detekt" dir="${basedir}"
+                                  fork="true" 
+                                  failonerror="true"
+                                  classname="io.gitlab.arturbosch.detekt.cli.Main"
+                                  classpathref="maven.plugin.classpath">
+                                <arg value="--input"/>
+                                <arg value="${basedir}/src/main/kotlin"/>
+                                <arg value="--excludes"/>
+                                <arg value="**/special/package/internal/**"/>
+                                <arg value="--report"/>
+                                <arg value="xml:${basedir}/reports/detekt.xml"/>
+								<arg value="--config"/>
+								<arg value="${basedir}/detekt.yml"/>
+                                <!--
+								<arg value="-b" />
+                                <arg value="${basedir}/reports/baseline.xml"/>
+								-->
+                            </java>
+                        </target>
+                    </configuration>
+                    <goals><goal>run</goal></goals>
+                </execution>
+            </executions>
+            <dependencies>
+                <dependency>
+                    <groupId>io.gitlab.arturbosch.detekt</groupId>
+                    <artifactId>detekt-cli</artifactId>
+                    <version>1.21.0</version>
+                </dependency>
+            </dependencies>
+        </plugin>
     </plugins>
   </build>
   <repositories>