Add SpotBugs tasks

Closes #3759

Signed-off-by: Chris Narkiewicz <hello@ezaquarii.com>

build.gradle

@@ -4,6 +4,7 @@
 // Due to this, the files layout is not the usual in new projects created with Android Studio / gradle. This file
 // merges declarations usually split in two separates build.gradle file, one for global settings of the project in
 // its root folder, another one for the app module in subfolder of root.
+import com.github.spotbugs.SpotBugsTask
 
 buildscript {
     repositories {
@@ -12,6 +13,9 @@ buildscript {
         maven {
             url 'https://oss.sonatype.org/content/repositories/snapshots/'
         }
+        maven {
+            url 'https://plugins.gradle.org/m2/'
+        }
         mavenCentral()
     }
     dependencies {
@@ -19,6 +23,7 @@ buildscript {
         classpath('com.dicedmelon.gradle:jacoco-android:0.1.4') {
             exclude group: 'org.codehaus.groovy', module: 'groovy-all'
         }
+        classpath 'gradle.plugin.com.github.spotbugs:spotbugs-gradle-plugin:1.6.6'
     }
 }
 
@@ -27,6 +32,7 @@ apply plugin: 'checkstyle'
 apply plugin: 'pmd'
 apply plugin: 'findbugs'
 apply plugin: 'jacoco-android'
+apply plugin: "com.github.spotbugs"
 
 configurations.all {
     exclude group: 'com.google.firebase', module: 'firebase-core'
@@ -68,6 +74,10 @@ if (taskRequest.contains("Gplay") || taskRequest.contains("findbugs") || taskReq
     apply from: 'gplay.gradle'
 }
 
+spotbugs {
+    toolVersion = '3.1.12'
+}
+
 android {
     lintOptions {
         abortOnError false
@@ -200,6 +210,30 @@ android {
         }
     }
 
+    android.applicationVariants.all { variant ->
+        String variantName = variant.name
+        String capVariantName = variantName.substring(0, 1).toUpperCase() + variantName.substring(1);
+        tasks.register("spotbugs${capVariantName}", SpotBugsTask) {
+            ignoreFailures = false
+            effort = "max"
+            reportLevel = "medium"
+            classes = fileTree("$project.buildDir/intermediates/javac/${variantName}/compile${capVariantName}JavaWithJavac/classes/")
+            excludeFilter = file("${project.rootDir}/findbugs-filter.xml")
+            source = fileTree('src/main/java')
+            classpath = files()
+            include '**/*.java'
+            exclude '**/gen/**'
+
+            reports {
+                xml.enabled = false
+                html.enabled = true
+                html {
+                    destination = file("$project.buildDir/reports/spotbugs/spotbugs.html")
+                }
+            }
+        }
+    }
+
     check.dependsOn 'checkstyle', 'findbugs', 'pmd', 'lint'
 
     compileOptions {