[build] compile with JDK 8 release api

resolves GH-244

Author: kares

Mavenfile

@@ -45,8 +45,8 @@ plugin( 'org.codehaus.mojo:build-helper-maven-plugin', '1.9' ) do
   execute_goal 'add-source', :phase => 'process-classes', :sources => [ gen_sources ]
 end
 
-plugin( :compiler, '3.8.1',
-        :source => '1.8', :target => java_target,
+plugin( :compiler, '3.9.0',
+        :source => '1.8', :target => java_target, :release => '8',
         :encoding => 'UTF-8', :debug => true,
         :showWarnings => true, :showDeprecation => true,
         :excludes => [ 'module-info.java' ],

pom.xml

@@ -246,7 +246,7 @@ DO NOT MODIFY - GENERATED CODE
       </plugin>
       <plugin>
         <artifactId>maven-compiler-plugin</artifactId>
-        <version>3.8.1</version>
+        <version>3.9.0</version>
         <executions>
           <execution>
             <id>compile-populators</id>
@@ -269,6 +269,7 @@ DO NOT MODIFY - GENERATED CODE
         <configuration>
           <source>1.8</source>
           <target>1.8</target>
+          <release>8</release>
           <encoding>UTF-8</encoding>
           <debug>true</debug>
           <showWarnings>true</showWarnings>