Set release instead of source&target

https://maven.apache.org/plugins/maven-compiler-plugin/examples/set-compiler-release.html

README.md

@@ -32,6 +32,10 @@ GNU General Public License Version 3. See [LICENSE](LICENSE)
 Contains images from Silk Icon Set v.1.3 (http://www.famfamfam.com/lab/icons/silk/)
 
 ## Development
+
+One needs JDK 11+ for building (requirement of some dependencies). Target release is still set to Java 8 (so resulting
+jar should be runnable under JRE 8).
+
 #### Build runnable JAR including all dependencies
 ```
 mvn clean package assembly:single

pom.xml

@@ -60,7 +60,7 @@
     </contributors>
 
     <properties>
-        <targetJdk>1.8</targetJdk>
+        <targetJavaRelease>8</targetJavaRelease>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
         <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
     </properties>
@@ -70,10 +70,12 @@
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-compiler-plugin</artifactId>
-                <version>3.1</version>
+                <version>3.10.1</version>
                 <configuration>
-                    <source>${targetJdk}</source>
-                    <target>${targetJdk}</target>
+                    <release>${targetJavaRelease}</release>
+                    <showDeprecation>true</showDeprecation>
+                    <showWarnings>true</showWarnings>
+                    <fork>true</fork>
                 </configuration>
             </plugin>
             <plugin>

src/test/java/com/brianmcmichael/sagu/ui/UploadWindowTest.java

@@ -10,8 +10,6 @@
 
 import org.testng.annotations.Test;
 
-import static org.testng.Assert.*;
-
 public class UploadWindowTest {
 
     // just for manual UI testing