fixed NPE when using maven checkstyle plugin

pom.xml

@@ -176,8 +176,6 @@
 				</executions>
 			</plugin>
 
-
-
 			<plugin>
 				<groupId>org.sonatype.plugins</groupId>
 				<artifactId>nexus-staging-maven-plugin</artifactId>
@@ -190,27 +188,11 @@
 				</configuration>
 			</plugin>
 
-			<!-- <plugin> -->
-			<!-- <groupId>org.apache.maven.plugins</groupId> -->
-			<!-- <artifactId>maven-shade-plugin</artifactId> -->
-			<!-- <executions> -->
-			<!-- <execution> -->
-			<!-- <phase>package</phase> -->
-			<!-- <goals> -->
-			<!-- <goal>shade</goal> -->
-			<!-- </goals> -->
-			<!-- </execution> -->
-			<!-- </executions> -->
-			<!-- <configuration> -->
-			<!-- <finalName>${project.artifactId}-${project.version}-with-dependencies</finalName> -->
-			<!-- </configuration> -->
-			<!-- </plugin> -->
-
 			<!-- Checkstyle -->
 			<plugin>
 				<groupId>org.apache.maven.plugins</groupId>
 				<artifactId>maven-checkstyle-plugin</artifactId>
-				<version>2.13</version>
+				<version>2.12</version>
 				<executions>
 					<execution>
 						<phase>test</phase>
@@ -218,7 +200,7 @@
 							<goal>check</goal>
 						</goals>
 						<configuration>
-							<configLocation>${project.basedir}/conf/quality-config/cs-conf.xml</configLocation>
+							<configLocation>${basedir}/conf/quality-config/cs-conf.xml</configLocation>
 							<includeTestSourceDirectory>true</includeTestSourceDirectory>
 							<encoding>UTF-8</encoding>
 							<consoleOutput>true</consoleOutput>
@@ -240,7 +222,7 @@
 					<threshold>Low</threshold>
 					<includeTests>true</includeTests>
 					<failOnError>false</failOnError>
-					<excludeFilterFile>${project.basedir}/conf/quality-config/fb-filter.xml</excludeFilterFile>
+					<excludeFilterFile>${basedir}/conf/quality-config/fb-filter.xml</excludeFilterFile>
 				</configuration>
 				<executions>
 					<execution>
@@ -257,10 +239,9 @@
 				<groupId>org.apache.maven.plugins</groupId>
 				<artifactId>maven-pmd-plugin</artifactId>
 				<version>3.2</version>
-
 				<configuration>
 					<rulesets>
-						<ruleset>${project.basedir}/conf/quality-config/pmd-ruleset.xml</ruleset>
+						<ruleset>${basedir}/conf/quality-config/pmd-ruleset.xml</ruleset>
 					</rulesets>
 					<includeTests>true</includeTests>
 					<targetJdk>${java.version}</targetJdk>