Close camunda-community-hub#203: use spotbugs to identify possible co…

…de problems

* added spotbugs gradle plugin
* added seperate job in GHA continous-integration that spotbugs analysis is always executed when a PR is created
* defined exclude rule that all generated classes beginning with $ are ignored

.github/workflows/continous-integration.yml

@@ -40,3 +40,29 @@ jobs:
             ${{ runner.os }}-gradle-
       - name: Build with Gradle Wrapper
         run: ./gradlew build --warning-mode=fail -Pmicronaut.runtime=${{ matrix.runtime }}
+
+  spotbugs:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Git Checkout
+        uses: actions/checkout@v2
+      - name: Set up JDKs with Matrix Build
+        uses: actions/setup-java@v1
+        with:
+          java-version: 8
+      - name: Cache Dependencies #see https://github.com/actions/cache/blob/master/examples.md#java---gradle
+        uses: actions/cache@v2
+        with:
+          path: ~/.gradle/caches
+          key: ${{ runner.os }}-spotbugs-gradle-${{ hashFiles('**/*.gradle*') }}
+          restore-keys: |
+            ${{ runner.os }}-spotbugs-gradle-
+      - name: spotbugs
+        id: spotbugs_checks
+        run: ./gradlew spotbugsMain
+      - name: publish spotbugs
+# TODO switch to orignial GHA when PR jwgmeligmeyling/spotbugs-github-action#10 is integrated
+        uses: arolfes/spotbugs-github-action@master
+        with:
+          path: '**/spotbugs/*.xml'
+          threshold: 0

config/spotbugs/exclude.xml

@@ -0,0 +1,5 @@
+<FindBugsFilter>
+  <Match>
+    <Class name="~.*\.\$.*" />
+  </Match>
+</FindBugsFilter>

gradle.properties

@@ -15,8 +15,9 @@ camundaVersion=7.14.0
 # Latest Jersey, that implements JAX-RS 2.1 API: see https://eclipse-ee4j.github.io/jersey/download.html
 jerseyVersion=2.33
 shadowJarVersion=6.1.0
+spotbugsVersion=4.6.0
 # Prevent upload of maven-metadata.xml.sha256/sha512 files to oss.sonatype.org
 # see https://issues.sonatype.org/browse/OSSRH-53695?focusedCommentId=887733&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-887733
 # see https://github.com/gradle/gradle/issues/11308#issuecomment-554317655
 systemProp.org.gradle.internal.publish.checksums.insecure=true
-org.gradle.parallel=true
+org.gradle.parallel=true

micronaut-camunda-bpm-feature/build.gradle

@@ -1,3 +1,4 @@
+import com.github.spotbugs.snom.Effort
 plugins {
     id("io.micronaut.library")
     id("java-library")
@@ -6,6 +7,7 @@ plugins {
     id("org.jetbrains.kotlin.plugin.allopen")
     id("maven-publish")
     id("signing")
+    id("com.github.spotbugs")
 }
 
 group = "info.novatec"
@@ -131,3 +133,22 @@ signing {
 configurations {
     testArtifacts
 }
+
+spotbugs {
+    ignoreFailures = true
+    effort = Effort.MAX
+    excludeFilter = file("${project.rootDir}/config/spotbugs/exclude.xml")
+}
+// Example to configure HTML report
+spotbugsMain {
+    reports {
+        xml {
+            enabled = true
+        }
+        html {
+            enabled = false
+            destination = file("$buildDir/reports/spotbugs/main/spotbugs.html")
+            stylesheet = 'fancy-hist.xsl'
+        }
+    }
+}

micronaut-camunda-bpm-feature/src/main/java/info/novatec/micronaut/camunda/bpm/feature/JettyServerCustomizer.java

@@ -122,7 +122,7 @@ static class ServletContextInitializedListener implements ServletContextListener
 
         protected static final EnumSet<DispatcherType> DISPATCHER_TYPES = EnumSet.of(REQUEST);
 
-        protected static ServletContext servletContext;
+        protected ServletContext servletContext;
 
         @Override
         public void contextInitialized(ServletContextEvent sce) {

settings.gradle

@@ -6,6 +6,7 @@ pluginManagement {
         id("com.github.johnrengelman.shadow") version "$shadowJarVersion"
         id("io.micronaut.application") version "$micronautApplicationPluginVersion"
         id("io.micronaut.library") version "$micronautLibraryPluginVersion"
+        id("com.github.spotbugs") version "$spotbugsVersion"
     }
 }