resolve maven stability warnings

pom.xml

@@ -42,7 +42,7 @@
 			<artifactId>lumberjack-mismatch</artifactId>
 			<scope>system</scope>
 			<version>1.0</version>
-			<systemPath>${basedir}/lib/Lumberjack_mismatch.jar</systemPath>
+			<systemPath>${pom.basedir}/lib/Lumberjack_mismatch.jar</systemPath>
 		</dependency>
 	</dependencies>
 
@@ -52,6 +52,7 @@
 			<plugin>
 				<groupId>org.apache.maven.plugins</groupId>
 				<artifactId>maven-compiler-plugin</artifactId>
+				<version>3.8.1</version>
 				<configuration>
 					<source>8</source>
 					<target>8</target>