Update to Gradle 6.0 and enable code compliing on Java 12 and Java 13

- add second parameter to FileSystems.newFileSystem
- disable build scan (only available in Gradle Enterprise: https://docs.gradle.org/current/userguide/upgrading_version_5.html#build_scan_plugin_2_x_is_no_longer_supported)

build.gradle

@@ -17,7 +17,6 @@ buildscript {
 
 plugins {
     id 'application'
-    id 'com.gradle.build-scan' version '3.0'
     id "com.simonharrer.modernizer" version '1.8.0-1'
     id 'me.champeau.gradle.jmh' version '0.4.8'
     //id 'net.ltgt.errorprone' version '0.8.1'
@@ -27,10 +26,7 @@ plugins {
     id 'org.beryx.jlink' version '2.16.2'
 }
 
-// use the gradle build scan feature: https://scans.gradle.com/get-started
-buildScan { termsOfServiceUrl = 'https://gradle.com/terms-of-service'; termsOfServiceAgree = 'yes' }
-
-gradle.startParameter.showStacktrace = org.gradle.api.logging.configuration.ShowStacktrace.ALWAYS 
+gradle.startParameter.showStacktrace = org.gradle.api.logging.configuration.ShowStacktrace.ALWAYS
 
 apply plugin: 'java'
 apply plugin: 'application'

gradle/wrapper/gradle-wrapper.properties

@@ -1,5 +1,5 @@
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-5.6.2-bin.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-6.0-bin.zip
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists

gradlew

@@ -154,19 +154,19 @@ if [ "$cygwin" = "true" -o "$msys" = "true" ] ; then
         else
             eval `echo args$i`="\"$arg\""
         fi
-        i=$((i+1))
+        i=`expr $i + 1`
     done
     case $i in
-        (0) set -- ;;
-        (1) set -- "$args0" ;;
-        (2) set -- "$args0" "$args1" ;;
-        (3) set -- "$args0" "$args1" "$args2" ;;
-        (4) set -- "$args0" "$args1" "$args2" "$args3" ;;
-        (5) set -- "$args0" "$args1" "$args2" "$args3" "$args4" ;;
-        (6) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" ;;
-        (7) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" ;;
-        (8) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" ;;
-        (9) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" "$args8" ;;
+        0) set -- ;;
+        1) set -- "$args0" ;;
+        2) set -- "$args0" "$args1" ;;
+        3) set -- "$args0" "$args1" "$args2" ;;
+        4) set -- "$args0" "$args1" "$args2" "$args3" ;;
+        5) set -- "$args0" "$args1" "$args2" "$args3" "$args4" ;;
+        6) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" ;;
+        7) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" ;;
+        8) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" ;;
+        9) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" "$args8" ;;
     esac
 fi
 
@@ -175,14 +175,9 @@ save () {
     for i do printf %s\\n "$i" | sed "s/'/'\\\\''/g;1s/^/'/;\$s/\$/' \\\\/" ; done
     echo " "
 }
-APP_ARGS=$(save "$@")
+APP_ARGS=`save "$@"`
 
 # Collect all arguments for the java command, following the shell quoting and substitution rules
 eval set -- $DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS "\"-Dorg.gradle.appname=$APP_BASE_NAME\"" -classpath "\"$CLASSPATH\"" org.gradle.wrapper.GradleWrapperMain "$APP_ARGS"
 
-# by default we should be in the correct project dir, but when run from Finder on Mac, the cwd is wrong
-if [ "$(uname)" = "Darwin" ] && [ "$HOME" = "$PWD" ]; then
-  cd "$(dirname "$0")"
-fi
-
 exec "$JAVACMD" "$@"

src/main/java/org/jabref/gui/JabRefDialogService.java

@@ -328,7 +328,7 @@ public boolean showPrintDialog(PrinterJob job) {
 
     @Override
     public Optional<Path> showFileOpenFromArchiveDialog(Path archivePath) throws IOException {
-        try (FileSystem zipFile = FileSystems.newFileSystem(archivePath, null)) {
+        try (FileSystem zipFile = FileSystems.newFileSystem(archivePath, (ClassLoader) null)) {
             return new ZipFileChooser(zipFile).showAndWait();
         } catch (NoClassDefFoundError exc) {
             throw new IOException("Could not instantiate ZIP-archive reader.", exc);