set maven compiler source and target to 11 and use property values in the maven-complier-plugin (#823)

Author: elliVM

pom.xml

@@ -43,8 +43,8 @@
     <changelist>-SNAPSHOT</changelist>
     <java.version>11</java.version>
     <junit.jupiter.version>5.7.1</junit.jupiter.version>
-    <maven.compiler.source>1.8</maven.compiler.source>
-    <maven.compiler.target>1.8</maven.compiler.target>
+    <maven.compiler.source>11</maven.compiler.source>
+    <maven.compiler.target>11</maven.compiler.target>
     <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
     <revision>0.0.1</revision>
     <sha1></sha1>
@@ -469,8 +469,8 @@
         <artifactId>maven-compiler-plugin</artifactId>
         <version>3.8.1</version>
         <configuration>
-          <source>11</source>
-          <target>11</target>
+          <source>${maven.compiler.source}</source>
+          <target>${maven.compiler.target}</target>
         </configuration>
       </plugin>
       <plugin>