refactor(ci): gradle 7.0.0 on jdk16

- update gradle.properties for spotless jdk16 work around
- diffplug/spotless#834

.drone.yml

@@ -191,7 +191,7 @@ steps:
           -c "select count(*) from pg_catalog.pg_tables;"
 
   - name: build
-    image: gradle:6.8-jdk15
+    image: gradle:7.0.0-jdk16-hotspot
     depends_on:
       - "cache pull"
       - "verify postgres"

.gitignore

@@ -165,5 +165,4 @@ dist/
 .idea/*
 backend/src/main/resources/basic_ledger.gnucash
 backend/src/main/resources/db/initialization/
-gradle.properties
 version

.gitlab-ci.yml

@@ -88,7 +88,7 @@ build-jar:
       - backend/build
 
 unit-tests:
-  image: gradle:6.8-jdk15
+  image: gradle:7.0.0-jdk16-hotspot
   stage: tests
   needs: ["build-jar"]
   script:
@@ -107,7 +107,7 @@ unit-tests:
       - backend/build
 
 h2-integration-tests:
-  image: gradle:6.8-jdk15
+  image: gradle:7.0.0-jdk16-hotspot
   stage: tests
   needs: ["build-jar"]
   script:
@@ -124,7 +124,7 @@ h2-integration-tests:
       - backend/build
 
 postgres-integration-tests:
-  image: gradle:6.8-jdk15
+  image: gradle:7.0.0-jdk16-hotspot
   stage: tests
   needs: ["build-jar"]
   services:

backend/Dockerfile.multistage

@@ -1,4 +1,4 @@
-FROM gradle:6.8-jdk15 AS build
+FROM gradle:7.0.0-jdk16-hotspot AS build
 COPY --chown=gradle:gradle . /home/gradle/src
 WORKDIR /home/gradle/src
 #RUN gradle --no-daemon bootJar

gradle.properties

@@ -0,0 +1,7 @@
+# work around for JDK 16
+# https://github.com/diffplug/spotless/issues/834
+org.gradle.jvmargs=--add-exports jdk.compiler/com.sun.tools.javac.api=ALL-UNNAMED \
+  --add-exports jdk.compiler/com.sun.tools.javac.file=ALL-UNNAMED \
+  --add-exports jdk.compiler/com.sun.tools.javac.parser=ALL-UNNAMED \
+  --add-exports jdk.compiler/com.sun.tools.javac.tree=ALL-UNNAMED \
+  --add-exports jdk.compiler/com.sun.tools.javac.util=ALL-UNNAMED